Source: Historia: Zeitschrift für Alte Geschichte, Bd. 45 ... · THE "MISSING DIMENSION" OF C. JULIUS CAESAR Julius Caesar opens his commentaries on the Gallic War with the famous

The "Missing Dimension" of C. Julius CaesarAuthor(s): Amiram EzovSource: Historia: Zeitschrift für Alte Geschichte, Bd. 45, H. 1 (1st Qtr., 1996), pp. 64-94Published by: Franz Steiner VerlagStable URL: http://www.jstor.org/stable/4436407 .

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THE "MISSING DIMENSION" OF C. JULIUS CAESAR

Julius Caesar opens his commentaries on the Gallic War with the famous line, "Gaul as a whole is divided into three parts, one of which is inhabited by the Belgae, another by the Aquitani, and a third by a people called in their own tongue Celtae, in the Latin Galli" (B.G. 1, 1). There follows a description of the tribes' features: their language, their characteristics, and their geo-political organization. This cannot be coincidental. It would not be far-fetched to assume that behind this seemingly innocent description of nature and population lurks military intelligence whose targets are climate, geography, population, together with ethnological considerations such as society, politics and religion.

In his description of Julius Caesar's military expertise and generalship, Suetonius tells us:

"In the conduct of his campaigns it is a question whether he was more cautious or more daring, for he never led his army where ambuscades were possible without carefully reconnoitring the country, and he did not cross to Britain without making personal inquiries about the harbours, the course, and the approach to the island. But on the other hand, when news came that his camp in Germany was beleaguered, he made his way to his men through the enemies' pickets, disguised as a Gaul" (Divus Iulius 58).

Julius Caesar played a major role in developing and exploiting the Roman war machine, but above all Caesar's other military skills (leadership, generalship, speed, motivating the troops, psychological warfare, courage) Suetonius emphasizes one which is ignored by many modern scholars, and that is his use of military intelligence.' Some scholars, however, who do deal with intelligence in the Roman army attribute to Caesar certain qualities in this field.2

There are only few military research papers about Caesar from the intelligence stand- point. It is absent from most Caesar monographs. For a discussion of Julius Caesar's intelligence, see R. M. Sheldon, Tinker, Tailor, Caesar, Spy: Espionage in Ancient Rome, Ann Arbor 1987, 94 ff. M. Gichon, "Military Intelligence in the Roman Army", Labor omnibus unus, ed. H. E. Herzig, Stuttgart 1989, 157 ff. Intelligence was defined as a "rmissing dimension of diplomatic history" in C. Andrew and D. Dilke, The Missing Dimension: Governments and Intelligence Communities in the Twentieth Century, Urba- na, Illinois 1984.

2 In the entry "Nachrichtenwesen" in the R.E., the following outlook is described: The reconnaissance and intelligence units were not organized in an orderly way in the Roman Army before Julius Caesar. However, reconnaissance, observers and trackers are mentioned but not as a permanent organization. Changes came with the master of the art of war,

Historia, Band XLV/l (1996) ? Franz Steiner Verlag Wiesbaden GmbH, Sitz Stuttgart



The "Missing Dimension" of C. Julius Caesar 65

In the following, we shall attempt to analyse Caesar's use of intelligence on two levels, according to the modern distinction: 1. strategic intelligence, answering the needs of a campaign - from informa-

tion gathering on the demographic, geographic and economic aspects of the enemy, up to the point of actual contact with the enemy.3

2. tactical intelligence, the acquisition of details relevant for conducting a battle. At the same time, it is worth stressing that the essentially modern distinc-

tion made here between the two categories is occasionally blurred, especially when dealing with ancient warfare.

1. Strategic intelligence

1. Sources of intelligence

Intelligence gathering takes many forms. De Bello Gallico IV, for example, contains a variety of information about the Germans beyond the Rhine which reached Caesar. In assessing the battle ability of the Germans, Caesar took into account their traditions, food, clothing, lifestyle and superstitions.4

In one of his descriptive digressions, Caesar hints at the sources he used in preparing for the Gallic campaigns. Thus, at IV,24, he quotes the Greek author Eratosthenes and mentions other Greek authors. He himself visited Cisalpine Gaul on his return from Spain in 67 B.C. (Suetonius, D.J. 8), and we can assume that he had access to the State archive and to reports sent from Gaul by various commanders. This does not mean that he had a reliable intelligence picture, and Plutarch (Caesar 23) tells us, for example, that there were people in Rome who did not believe that the island of Britain existed. This was probably the case at that time with other distant provinces as well.

Intelligence gathering is expressed in De Bello Gallico in phrases such as Caesari renuntiatur, Caesar... certiorfactus,5 Caesar cognovit without stating the source of the intelligence.6 Thus, for example, Caesar, who was then at Geneva, was told that "the Helvetii were minded to march through the land of

Caesar, as part of comprehensive tactical and organizational changes. See Reincke, RE. XVI.2, 1935, "Nachrichtenwesen" 2. Militarisches, col. 1500.

3 For use of modern terminology of strategic and tactical intelligence, see N. J. E. Austin, Ammianus on Warfare (Collection Latomus 165), Brussels 1979, p. 22, 116. See also E. Wheeler, "Methodological Limits and Mirage of Roman Strategy", The Journal of Milita- r-y History, 57, 1993, 21 ff.

4 B.G. IV,2,3-4. 5 B.G. I,10. 6 See: B.G. VI,2.



66 AMIRAM Ezov

the Sequani and the Aedui into the borders of the Santones..." (B.G. 1,10). In another case it is stated that "All this [Dumnorix' political aspirations and treachery] Caesar learnt, and to confirm these suspicions he had indisputable facts. Dumnorix had brought the Helvetii through the borders of the Sequani; he had caused hostages to be given between them..." (B.G. 1,19), and at 1,28 it is reported that Caesar found out about the escape of the Verbigeni from the Helvetian camp. These three instances are typical: Caesar does not state his sources, but he does reveal that he obtained information from distant sources, and he may even have had a source or sources of information within the Helvetian camp itself.

How was information obtained? In some cases the sources are stated. For example:

a. Caesar questioned prisoners as to why Ariovistus avoided a decisive battle, and he discovered that the Germans had a custom that "their matrons should declare by lots and divinations whether it was expedient or not to engage, and the matrons declared that heaven forbade the Germans to win a victory, if they fought an action before the new moon" (B.G. 1,50).

b. After the first campaign season, while Caesar was wintering in Cisalpine Gaul, "frequent rumours were brought to him, and despatches also from Labi- enus informed him, that all the Belgae... were conspiring against Rome and giving hostages to each other" (B.G. 11,1).

c. When Caesar decided to go to war against the Belgae, he came to the army and ordered the Senones and other Gauls who bordered the Belgae to investigate their actions and report to him. In all their messages they reported the recruitment of armies and their concentration in one place (B.G. 11,2). Later, to Caesar' s questions regarding the war plans, troop numbers and battle strength of the Belgae, the Remi replied that '... concerning their numbers, ... they had

exact information in all particulars, because, as they were closely connected by relationship and intermarriage, they had learnt how large a contingent each chief had promised for the present campaign in the general council of the Belgae." The information follows (B.G. 11,4).

d. Caesar learnt from exploratores and from the Remi that the Belgae were not far away (B.G. II,5).

In these passages, we see four different sources of intelligence: 1. Prisoners. While most information received from prisoners usually per-

tained to the immediate battle, in this case it concerned the customs and superstitions of the Germans. We may note that Caesar considered this sort of information relevant to his forthcoming confrontation with the Germans. He did not overlook psychological and religious factors.

2. Legates' despatches (this raises the question of the identity of the "messengers"'). From the way it is presented in the text, the use of legates for gathering information seems to have been routine. In one case, when Quintus




Cicero was pressed by the Nervi, in the year 54, it is said that the more serious the siege operations became, "the more frequent were the despatches and messengers (litterae nuntiique) sent to Caesar" (B.G. V,45).

3. Neighbouring allies (e.g., Senones, Remi). The relative advantage of allies was their knowledge of the language and customs and their ability to move around undetected.7 The information given by allies was of unique value. No other existing intelligence arm could have supplied what was demanded of the Remi and the Senones.

4. A patrol known as exploratores which was not used strategically but tactically to supply information about the current location of the enemy in the vicinity of the main force.

In addition, it seems that rumours played a large part in the transfer of information. We do not know who spread these rumours, but in one passage Caesar describes a rumour passing through Gaul: "Speedily the report thereof was carried to all the states of Gaul. As a matter of fact, whenever any event of greater note or importance occurs, the Gauls shout it abroad through fields and districts and then take it up in turn and pass it on to their next neighbours; as happened on this occasion" (B.G. VII,3). Accordingly, it would appear that Caesar heard the rumours echoing across mountains and rivers as they passed through the allied tribes.

Sometimes luck played its part in the obtaining of information. "In the camp of the Helvetii were found, and brought to Caesar, records written out in Greek letters, wherein was drawn up a nominal register showing what number of them had gone out from their homeland, who were able to bear arms, and also separately children, old men, and women." The sizes of each tribe follow (B.G. 1,29).

The need for "strategic" intelligence is most manifest in the planning for the invasion of Britain which was "beyond the confines of the inhabited world" and even regarded as mythical (Plutarch, Caesar 23).8 Suetonius exaggerates in his claim that Caesar "did not cross to Britain without making personal inquiries about the harbours, the course, and the approach to the island" (D.J. 58). The picture from De Bello Gallico is slightly different. Since the island was a closed book to the Gauls, Caesar summoned traders and tried to learn from them the size of the island, the nature and power of the tribes living in it, their method of warfare and their customs (B.G. IV,20). Only after this attempt was unsuccess- ful did he find a suitable scout, the tribune Gaius Volusenus, and send him with a ship of war "... to spy out everything and to return to him at once" (ut

7 See also: B.G. 1,31. 8 Plut., Caesar 33: The excuse Caesar gave for the expedition was the aid which the Britons

gave to his enemies in Gaul, see B.G. IV,20.



68 AMIRAM Ezov

exploratis omnibus rebus... revertatur, B.G. IV,21).9 Caesar himself set off with his forces for the territory of the Morini, from which was the shortest passage across to Britain, and then prepared his army for the invasion and settled down to wait for his intelligence reports.

Caesar appears to have required Volusenus to furnish the very facts he had failed to obtain from the traders ("to gain such knowledge before he made the venture...," B.G. IV,2 1); but it is more likely, following Suetonius, that Caesar required him specifically to furnish data necessary for the invasion itself: the course, the approach to the island, the currents, harbours. It is unreasonable to assume, despite the vague expression "to spy out everything", that Caesar expected one man to collect all the wide ranging intelligence he himself had failed to obtain from the traders. Indeed, Volusenus did not even disembark, apparently for fear of the natives, and all his findings were based on what he could see from the deck of his ship. He returned after four days' absence and reported what he had seen with his own eyes. Caesar's invasion of Britain, then, was based on intelligence collected by one man in just a few days. If Caesar had expected more of Volusenus, he could have sent another intelligence gathering expedition out, but he did not do so. It must be said, however, that time was not on his side, with winter fast approaching (B.G. IV,20). Perhaps Caesar did not attach much importance to information concerning enemy strength, and Vo- lusenus' intelligence satisfied him, even though it turned out to be inadequate for the campaign.

2. The effect of intelligence reports on decision making at the strategic level

The Volusenus affair illustrates not only the way targets for intelligence missions were defined but also the effect of intelligence on the plan of operation and the degree of its success. While anchored off the coast of Britain, Caesar assembled his legates and tribunes to tell them what he had heard from Voluse- nus and what he intended to do. In this sense, Volusenus' report had some influence on the battle plan; but the failure of the first landing may be attributed to insufficient intelligence concerning the enemy and the lie of the land (or in this case, of the sea as well), and exposes the worthlessness of Volusenus' report.

Many other cases show that Caesar changed plans and devised campaigns according to intelligence reports. At the end of the first campaign year (57 B.C.), for example, while Caesar was wintering in Cisalpine Gaul, many rumours reached him (as did Labienus' reports) to the effect that all the Belgae were conspiring against the Roman people, and giving each other hostages

9 For evidence of the bravery of Volusenus, see: B.G. III,5.




(B.G. 11, 1). Following up on this intelligence, Caesar recruited two new legions in Cisalpine Gaul and sent them at the beginning of summer into Inner Gaul with a legate at their head. Caesar, who may have been organizing his forces for a campaign against Illyria, altered his dispositions because of this intelligence, and was forced to become deeply involved in Gaul.10

In 53 B.C., Caesar believed that a great rebellion was in the offing. The intrigues of the Treveri, their incitements, their alliances with the Germans, the exchange of hostages, their alliance with Ambiorix; the war preparations of the Nervii, Aduatuci and Menapii - all these things were known to Caesar (B.G. VI,2). Caesar came to the conclusion that he had to move against the Nervii even before the end of winter. Once again, intelligence played a part in forming the overall plan of operation.

To sum up this section: 1. Because of his penetration into unknown territory, Caesar made exten-

sive use of campaign intelligence. His intelligence requirements embraced a very wide range of demands, from geo-political, through ethnological and psychological , to purely military data. His need to turn territory unfamiliar to the soldiers into familiar territory should also not be underestimated.

2. Strategic intelligence was also required for the successful execution of Caesar's general strategy which entailed striking at the weak points of an enemy who had numerical advantage. The main aim of his plan of operations was to prevent the Gauls from massing their forces for a concerted attack. Caesar says as much while explaining his plan of campaign to Diviciacus the Aeduan (B.G. 11,5)."

3. Intelligence was the cornerstone of strategic decisions such as the general concentration on Gaul, and operational decisions on the timing of attacks and troop movements, such as in the great uprising in Gaul in 53 B.C.

4. The invasion of Britain illustrates an apparent paradox. While Caesar's intelligence requirements were certainly high, the practical results were very limited and contributed little to the war effort. Perhaps, then, in this case, Caesar attached less importance to specific information about the military qualities of the enemy, and more to the unknown sea passage and the island's harbours.

10 For this evaluation see A. Sherwin-White, "Caesar as an Imperialist", G&R, 2nd. Ser. 4,

1957, 36 ff. I I In the year 57 when the Belgae were massing a huge force (300,000 according to Caesar's

version against 40,000 of Caesar's soldiers), Caesar sent the Aedui tribe to take over the

land of the Bellovaci, in order to split the enemy force and to threaten their supply lines.

The splitting brought about the collapse of the coalition.



70 AMIRAM Ezov

II. Tactical intelligence

The role of "field-intelligence" units on the modern battlefield is defined as "the collection of all information concerning enemy forces, enemy military ability, the nature of the terrain, lines of provision... and of particular importance is information on the disposition of enemy forces, including data on the identity of enemy units, enemy organization, troop composition, strength, direction of movement, as well as morale and fighting fitness."12

The tactical level of intelligence gathering deals, then, with the obtaining of information which directly serves the battle plan. This tentative definition, despite its modern character, may serve as a criterion by which to examine the operational methods of the three types of "intelligence agents", the cavalry, exploratores, and speculatores in the Gallic and Civil Wars, and the exploita- tion of other sources of information, such as prisoners and deserters.

A. Cavalry

Hot on the heels of the Helvetii, Caesar equitatum ... omnem ... praemittit qui videant quos in partes hostes iterfaciant (B.G. 1,15). This cavalry which Caesar had raised from the whole of the province numbered four thousand. Its mission was to follow the enemy, a classic role for cavalry - pursuit and the application of continuous pressure on the enemy -, and there is also an intelligence function.13

The intelligence aspect of the use of cavalry, as opposed to the "routine" tasks of defending the legion's flank and harrying a retreating enemy, has not received much attention in modem research. This despite Caesar's apparently extensive use of cavalry for intelligence purposes. In 57 B.C., for example, when Caesar was faced with 300,000 Gauls, he ordered his horsemen to engage in daily cavalry skirmishes with the enemy in order to test their strength and to build up the courage of his own men (B.G. 11,8). In another instance, during the siege of the Aeduan town of Gergovia, Caesar sent several troops of horsemen out in all directions making more noise than usual in order to distract the enemy's attention from the direction of the impending assault (B.G. VII,45). The tasks executed by the horsemen in these cases are skirmishing, intelligence gathering and decoying - all in the field of operational intelligence.

12 See Encyclopaedia Britannica, 1950, s.v. "Intelligence".

13 On the function of the cavalry in Caesar's army see L.Keppie, The Roman Army, London

1984, p. 100. For a criticism of the use of the cavalry in Caesar's army see Sheldon (cit.

n. I).




Besides its traditional roles, then, the cavalry served an intelligence function which included skirmishing, advance guard reconnoitering, locating and securing lines of communication, information gathering, and the appropriation of sources of information.'4

B. Information from captives and deserters on the eve of battle

Caesar made extensive and systematic use of prisoners of war as a source of intelligence, seeking to obtain from them such information as the combat readiness of the enemy, as in the following case:

"At dawn Labienus was in possession of the summit of the height, and Caesar was no more than a mile and a half from the enemy's camp; and, as he learnt afterwards from prisoners, neither his own approach nor that of Labienus was discovered" (B.G. 1,22).

Having set up his first camp on British soil, Caesar "learnt from prisoners where the enemy's forces had taken post..." (B.G. V,9). Caesar also learnt from prisoners and deserters that the Thames could only be crossed at one place on foot, and that this ford was protected by a large enemy force and fortified with sharp stakes, both above and below the waterline (B.G. V,18).15 In 52 B.C., during the siege of Avaricum, Caesar learnt from prisoners of an ambush planned for the next day against his foragers, to which Caesar made an immediate military response (B.G. VII,18).

Information from prisoners was not accepted without verification and criti- cal assessment. An aside on the information obtained from prisoners captured in the territory of the Bellovaci, that "most [of the prisoners] were in agree- ment" - consentientibus pluribus (B.G. VIII,8), reveals that Caesar interrogated a number of prisoners, compared their versions and in this way verified their stories. A similar procedure was adopted with deserters (perfugae). The information concerning the obstacles in the Thames was drawn from deserters, as

14 Most of the cavalry men were Gauls or Germans and had the advantage of knowing the land and were able to supply more topographical information. When, for example, Caesar lost contact with the Helvetians at Senvigne, he equitatum omnem ante se mittit (B.G. I,21) and sent an exploratores unit ahead of the cavalry. The dispatch of cavalry and expeditionary and reconnaissance forces appeared common practice. In one of the episodes in B.G. V,47 (in the year 54) when Caesar was in movement toward meeting the surrounded Q. Cicero, the information about the arrival of the legate Crassus was learned from the antecursores, the advance party. In another place (B.A. 12,1 ) information about the approach of the enemy was brought per speculatores and antecessores equites. For additional examples of using the cavalry for intelligence, see B.G. 111,25.

15 For the use of prisoners in obtaining intelligence information, see also VI,32, V,48.



72 AMIRAM Ezov

were the plans of Vercingetorix at the siege of Alesia (B.G. VII,72). Such information was normally considered unreliable unless verified and cross-checked with other sources of information. During the siege of Gergovia, Caesar "noticed that a hill held by the enemy, and on the previous days scarcely visible for the crowd upon it, was undefended. Surprised thereat, he asked deserters, a large number of whom were flocking to him daily, for the reason. All agreed in stating, what Caesar himself had already learnt through scouts (exploratores)..." (B.G. VII,44).

The uniqueness of intelligence from prisoners is the view it provides of the enemy from the inside, on matters such as battle readiness, intentions, routines, morale, special measures, topography, exact organization and location of the force, none of which could be obtained through the usual means of patrols and observation posts. The prudent use of prisoners by Caesar on his many marches into unknown territory contributed greatly to his correct assessment of a given situation.

C. Exploratores

l. The Gallic War

In 58 B.C., Caesar found himself with the Aedui facing the imminent invasion of the Helvetii. The Allobroges, who had territory on the other side of the Rhone, retreated to Caesar and informed him that they had nothing left there but the bare ground. Accordingly, Caesar decided to forestall the arrival of the Helvetii before they could destroy the property of his allies. This is how Caesar describes his first contact with the Helvetii:

"This river (the Arar = Saone, a tributary of the Rhone) the Helvetii proceeded to cross by rafts and boats fastened together. When Caesar's scouts (exploratores) informed him that three quarters of the Helvetian forces had actually crossed, and that about a quarter remained on the near side of the river Saone, he left camp in the third watch with three legions..." (B.G. 1,12).

Apart from the pastoral, geographical and political description presented in this passage, Caesar reveals for the first time a new intelligence arm, the

detachment or company of exploratores.'6 We may make out from the passage

16 The verb explorare is translated in Cassell's as "to spy, search out, to reconnoiter out."

Rice Holmes in his commentary on The Gallic War explains that "The English equivalent

is not 'scout', but 'patrol'." Scout is properly called speculatores. Even so, many translate

the term as "scout". See for example the Loeb edition and other translations. I prefer to

leave the term and translate it according to the context.




what this unit's mission was, but neither here nor anywhere else in Caesar's writings is there any reference to its size or composition. We can only infer from the situations and military contexts in which it appears, what use was made of this unit, and what its tactical role might be. In this particular case, the intelligence required from the exploratores is in the context of making contact with the Helvetii. The exploratores were sent to locate the crossing point of the Helvetii, and they appeared to have kept the enemy force under observation. Although it is not stated in the text, it would appear that the observation was conducted in secrecy, with none of the intentional skirmishing we have seen performed by the cavalry. The exploratores were on a similar mission during the siege of Cenabum in 52 B.C., where they maintained a listening post or quiet patrol at a ford: "A little before midnight the men of Cenabum moved out in silence from the town and began to cross the river. This was reported to Caesar by the scouts (per exploratores); and setting the gates on fire, he sent in the legions which he had ordered to be ready for action, and took possession of the town" (B. G. VII, 1). We may assume, therefore, that the operation took the form of a quiet observation post at a key tactical point, following an earlier assessment by Caesar that the town was about to be abandoned by its inhabitants under cover of darkness.

More information concerning the type of intelligence required from the exploratores may be gleaned from the following passage:

"On the same day his scouts (exploratores) informed him that the enemy had halted close under a height eight miles from the Roman camp. A party was sent to reconnoitre the height, and to see what kind of ascent a detour might afford. ... Publius Considius, reputed a past master in the art of war, who had seen service in the army of Lucius Sulla and afterwards in that of Marcus Crassus, was sent forward with the scouts (exploratores)"17 (B.G. 1,21).

This passage contains several important hints concerning the activity of the exploratores:

a. The exploratores were sent eight Roman miles (about twelve kilometres) away from the main force to locate the enemy. The distance from the camp is not great, but one should also bear in mind that it is dependent on actually locating the enemy, and does not in itself reflect the true range of the operation. We do not have data on fixed regulations concerning the operating range of a mounted advance force in Caesar's army, but even in other mounted forces, both historical and modern, the advance guard never strays more than fifteen kilometres from the main force, a distance which still permits communication

17 The mountain was identified as Senvigne, six miles east of the river. See Rice Homes, Caesar, De Bello Gallico, Oxford 1914, p. 24.



74 AMIRAM Ezov

and security.'8 The present case of locating the enemy may, then, be an instance of routine procedure before an impending battle. In another case, exploratores inform Caesar that the army of Ariovistus is 24 miles (36 km) away from his own force (B.G. I,4 1). The operating range may, therefore, be as much as half a day's ride away from the main force, according to requirements. One may suspect that the exploratores had received explicit instructions to patrol deeper into enemy territory than was usual.19

b. The distance and the nature of the mission clearly show that the force was mounted, and that the standard of horsemanship was high, given the need for secrecy, alertness and speed.

c. No less significant in the passage are the intelligence demands placed upon the unit: "to reconnoitre the height, and to see what kind of ascent a detour might afford." The exploratores had to provide the topographical information necessary to conduct an assault on the enemy position, if possible, by way of a flanking manoeuvre. In other words, they had to provide the intelligence components on which the tactical plan could be built. The exploratores also provided the topographical information required during the siege of the Aeduan town of Gergovia in 52 B.C. (B.G. VII,44).20

d. It appears that the commander (a centurion?) was specifically appointed for the task on the merits of his skill and experience. According to the passage, Considius was a very old man, if he had served in the 80s in Sulla's army, and he was very experienced. Even so, he did not stand up to the task of intelligence gathering, as Caesar narrates:

"At this moment Considius galloped back to him, saying that the mountain he had wished Labienus to seize was in possession of the enemy: he knew it by the Gallic arms and badges. Caesar withdrew his own troops to the nearest hill, and formed line of battle. ... At length, when the day was far spent, Caesar learnt per exploratores that the height was in possession of his own troops, and that the Helvetii had shifted their camp, and therefore that Considius in sheer panic had reported to him as seen that which he had not seen" (B.G. 1,22).

This passage reveals that the report of Considius, commander of the exploratores, was inaccurate; yet at the same time, Caesar continued to receive further

18 On the operation of the cavalry on reconnaissance missions during war, see R. Davies, "Roman Cavalry", Arch. Jour., 125, 1969, p. 117. See also K. Dixon and P. Southern, The Roman Cavalry, London 1992, 137 ff.

19 An estimation of the operating range of the cavalry is complex. The estimation is that trained cavalry could travel 70 miles in 24 hours during operations. See R. Davies (cit. n. 1 8),p. 117.

20 In this case the information was verified by deserters.




intelligence reports from the exploratores, verified versions and thereby obtained a reliable picture. It is possible that the passage demonstrates the differ- ence between the report of a professional and trained unit, and that of a soldier experienced in warfare but untrained in intelligence operations. We find the appointment of commanders of exploratores for specific missions during the selection of a campsite, but it is clear that the appointment is not permanent but for the task at hand.

From the discussion so far it transpires that the exploratores were a special operations intelligence body which by its very nature had to have specific professional skills, such as the abilities to observe and to move with stealth. These required special training. All the same, the only organizational feature hinted at, clearly, if indirectly, is that the patrol was mounted ("Considius galloped back"). Indeed, the very nature of the mission demanded it, and, as we shall see, the exploratores were stationed next to the mounted advance guard in the column. If we combine this fact with the known origin of Caesar's cavalry, we may conclude that the exploratores originated in the auxiliary cavalry. Another feature may be inferred from the appointment of Considius. Such an ad hoc appointment would seem to imply that the unit was not permanent with an established command structure, but a small unit which required a commander suitable to the particular situation (which Considius turned out not to be).

The next passage sheds light on Caesar's use of the exploratores in the column leading up to contact with the enemy:

"... through Diviciacus (the one person in whom Caesar had absolute confidence) a route was found out to lead the army through open country, by a detour of more than fifty miles. In the fourth watch, as Caesar had said, the march began. On the seventh day of continuous marching the scouts reported that the forces of Ariovistus wer four-and-twenty miles away from our own" (B.G. 1,4 1).

The exploratores operated at a very great distance from the main force in

this instance - a day's march. The mission was clearly to locate the enemy and prevent ambushes in the line of march.21 Another passage testifying to the

position and mission of the exploratores in the column is the following: "So soon as he perceived that all the forces of the Belgae had been concentrated and

were coming against him, and learnt from the scouts (exploratores) whom he

had sent and from the Remi that they were now not far distant ..." (B.G. 11,5). It

is worth noting, however, that the pathfinder in the first case was the Aeduan

leader, Diviciacus, and not the exploratores. Without jumping to conclusions here, one would have expected this to be a mission for the exploratores.

21 Compare with Vegetius, Epitoma Rei Militaris 111,6, which, although late, reflects the

ancient historical reality.



76 AMIRAM Ezov

Furthermore, in another instance, during the campaign against the Belgae (57 B.C.), Caesar relates innocently: "After a three days' march through their borders Caesar found out from prisoners that the river Sabis (Sambre) was not more than ten miles from his camp, and that across the river all the Nervii were in position, awaiting there the coming of the Romans..." (B.G. 11,16). Where, then, are the exploratores? Caesar continues a little later: "Upon this information Caesar sent forward scouts (exploratores) and centurions to choose a fit place for the camp" (B.G. II, 17). According to the literal sense of this passage, the exploratores did not operate ahead of the column in this instance. At any rate, the enemy dispositions were learned through prisoners, and only then were exploratores sent to locate a site fit for the camp. If so, it would not be going too far to assert that there were no fixed battle procedures according to which exploratores had to be sent ahead of the column. It was rather a matter which was left to Caesar's discretion according to the circumstances, particularly when contact with the enemy was anticipated. A similar case is reported by Hirtius. The legate Caninius was conducting a campaign against the invading Senonian, Drappes, in 51 B.C.:

"After his success Caninius discovered from prisoners that a part of the force was with Drappes in camp not much more than twelve miles away. He ascertained this from several persons ... Distributing one legion between the three camps, he himself led off the other in light order. When he had come nearer the enemy, he learnt from the scouts (ab exploratoribus) he had sent forward that, according to the general rule of the natives, the higher ground had been abandoned and the camp brought down to the banks of the river..." (B.G. VIII,36).

Caninius learnt of the enemy's presence, eighteen kilometres away, from prisoners, and not from his scouts. The exploratores were sent ahead only when the legion began to march, and their mission was to locate the enemy and the enemy camp. It should be noted that at the head of the column alongside the exploratores rode the mounted advance guard which Caesar calls the "forerun- ners" (antecursores, B.G. V,47). It is matter of some doubt whether this was a commonly used term for the advance guard.22

At B.G. II,17 (above), another role for the scouts was mentioned, the location of a campsite. Such a mission required a knowledge of the area and an appreciation of the military factors which had to be taken into consideration when setting up a camp. It seems that for this reason centurions were attached to the unit.23 Polybius (VI,41), discussing the camping arrangements of the army,

22 For an additional reference to the advance mounted guard force, here termed antecesso-

res,seeB.A. 12,1. 23 On the establishment of a camp in the Roman army, see Polybius, VI,27.




states that "when the column approaches the campsite, a tribune and the centurions who are chosen for the task each time go ahead." This means that the attaching of centurions to the mission of the exploratores should be interpreted in the context of the usual procedure for choosing a campsite, and not as significant for the command structure of the unit of exploratores. Selecting a campsite involved considering the location, security, access, and the camp's interior. These factors required the judgement of an experienced senior. The exploratores were no more than tools in the hands of the centurions in carrying out this particular mission. The size of the unit of exploratores cannot be accurately assessed from the information we have on its command structure, but we may infer that it was smaller than a century. We may also infer, from the appointment of Considius, that the exploratores did not have a fixed command structure, but that officers of the rank of centurion were appointed as the nature of each mission demanded.

Exploratores were not brought into operation only at the highest level of command, but were also used at the level of the single legion. Galba, commander of the Twelfth Legion, was wintering with his legion in a hamlet of the Veragri called Octodurus when the following incident occurred:

"Several days had passed in winter quarters, and Galba had given orders for corn to be brought in from the neighbourhood, when on a sudden his scouts (exploratores) informed him that in the night every soul had withdrawn from that part of the hamlet which he had granted to the Gauls, and that the heights overhanging were occupied by an enormous host of Seduni and Veragri" (B.G. 111,2).

The passage is sufficient to show that exploratores were used continuously, not just on the march, but also when the legion was inactive. Their missions included securing the camp and locating potential signs of rebellion in the area. It was the exploratores who discovered the movement of the tribes who were bent on renewing the war. On receipt of the information Galba called a counsel of war; but before he could plan properly, the attack began.

2. Allied exploratores

So far we have not assumed anything about the origin of the exploratores, not least because of the lack of information. Two pieces of circumstantial evidence afford some hints:

a. The unit appears to have originated in the cavalry which itself was of mainly noble Gallic, and German, origin.24

24 See Keppie (cit. n. 13), p. 100.



78 AMIRAM Ezov

b. Natives would have an advantage in intelligence operations due to their knowledge of the terrain and the local customs.

It is also clear from the evidence that the exploratores dealt with so far belonged organically to the auxilia of the legion, if only because of the sensitiv- ity of the missions imposed upon them, which assumed a high degree of loyalty and trust. It is possible, incidentally, that centurions were attached to the exploratores as a sort of internal security precaution on missions which were of particular importance, such as the selection of a campsite.

It transpires, however, that intelligence demands required complementary sources of information, especially where long distances were involved, or where the information could not be obtained by the legionary patrols. In 53 B.C., Caesar decided to cross the Rhine to punish the Germans for giving aid to the Treveri. The Ubii, wishing to prove their loyalty, were asked to provide information concerning lines of advance into the country of the Suebi (B.G. VI,9). In addition, Caesar ordered them ut crebros exploratores in Suebos mittant. The Ubii accomplish the mission and report on Suebian movements. A similar mission in a similar context appears a little later: "When Caesar had ascertained through scouts of the Ubii (per Ubios exploratores) that the Suebi had retired into the forests, he decided to advance no farther, fearing scarcity of corn, because, as above mentioned, all the Germans care naught for agriculture" (B.G. VI,29). The task of locating the enemy, then, was imposed on allied scouts. There was a clear advantage in this procedure due to their unhindered freedom of movement and their knowledge of the terrain. That allied scouts, who were not in a clearly defined unit, could be called exploratores, may shed light on Caesar's use of the term in general.25

3. Were the exploratores in the Gallic War a regular unit of the army?

Caesar did not bother to leave to future generations any description of the unit's organization, size, origin or structure. All our inferences are circumstantial, and the facts must be weighed up in the following way to arrive at any conclusions:

1. On the negative scale stand: a. The term exploratores is used in a very general way, being applicable

both to allies and to the enemy. It is even applicable, in part, to the speculatores (see below). Although it is impossible to draw any definitive conclusions from the way this term is used, it does seem likely that it was not used as a technical term for a regular, well-defined unit.

25 Caesar makes an "undistinguished" use of language when he describes the activity of (he enemy reconnaissance. See, for example, V,49; VII, 16.




b. There is no evidence for a fixed command structure. If there was a commander directly in charge of the exploratores, for which we have no evidence, he would be below the rank of centurion. When the mission required a high-level assessment, or involved selecting a campsite, centurions would be attached ad hoc. This could all point to an irregular and a relatively small force.

c. The exploratores are not used consistently for missions where one would have expected them to be used. There seems to have been no fixed operating procedure. Sometimes the exploratores would be sent ahead to locate the enemy, and sometimes this mission would be undertaken by other units, but not at a great distance from the main force.

d. Caesar also used other types of troops for intelligence gathering and patrols, such as speculatores, cavalry and allied scouts. This means that the exploratores were not an integral part of Caesar's military procedure.26

2. On the positive scale stand: a. Caesar operated a variety of intelligence arms and made extensive use of

the scout unit whose missions included: 1. gathering intelligence about enemy movement, location, and strength; 2. locating and opening lines of communication; 3. serving as advance guard when contact with the enemy was imminent; 4. selecting a campsite; 5. deep penetration patrols; 6. one component of camp security; 7. locating potential pockets of rebellion.

b. The missions required certain skills: horsemanship, observation, camou- flage, situation assessment. One might speculate therefore, that experienced soldiers were chosen for these missions, and that they, in time, became special- ists at intelligence work.

c. The exploratores were a mounted body, originating as far as we can see from cavalry units. This fact, when taken together with the professional requirements of the job, leads one to suppose that the exploratores were chiefly drawn from the auxilia, such as the legion's Gallic alae.27

The pros and cons of the case lead us to the conclusion that the exploratores were a unit or individuals allocated to a given mission, probably with a degree of specialization in the field of intelligence, yet irregular, and not part of the fixed military structure.

26 The assumption here is that despite his operational flexibility, Caesar acted according to accepted standards of military procedure. See Keppie (cit. n. 13), p. 101, who claims that Caesar received the army as he found it, and directed it according to his interests, although there is nothing that shows he made any changes in the army ranks or organization.

27 Keppie (cit. n. 13), p. 79, 100.



80 AMIRAM Ezov

D. Speculatores

1. The Gallic War

The following affair brings to light another particular aspect of intelligence gathering. During the Belgian conspiracy of 57 B.C., Caesar had to go to the rescue of the Remian town of Bibrax, and found himself in an awkward confrontation with the Belgian army by the river Axona (Aisne). Their failure in battle, and news of the approach of the Aedui, induced the Belgae to decamp and return to their own territory. The decision caused much panic in the Belgian host, as Caesar reports:

"... so that they made their departure seem like to a flight. Caesar learnt this at once through his scouts (per speculatores); and fearing an ambush, because he had not yet perceived the casue of their departure, he kept the army and the cavalry in camp. At break of day, when the information had been confirmed by reconnaissance (ab exploratoribus), he sent forward all the cavalry to delay the rearguard" (B.G. II, 1 1).

This passage reveals another intelligence gathering unit, the speculatores.28

Of interest to us is the distinction made between the two types of intelligence activities. Caesar clearly uses the exploratores here to verify information arriv- ing from a different source. In other passages, the terminological and functional distinction is not so clear, but here, the withdrawal of the Bellovaci from the enemy camp was reported to Caesar by speculatores who must have either been disguised and stationed within the camp as spies, or maintained a listening post near the enemy camp to thwart surprises from that direction. The latter may be more likely, given that the Bellovaci were described as leaving magno cum strepitu et tumultu. We do not know how many speculatores were involved, but the number was surely small, the size of a squad, as befitting its secretive nocturnal mission. At the same time, we see that Caesar was in no hurry to act, but waited for confirmation from another source. To verify the information, he sent the exploratores at dawn. An analysis of the text appears to show that their mission required close pursuit of the enemy with the possibility of actual contact. The two intelligence types are therefore clearly distinguished by their functions. The speculatores gather information through spying, while the ex-

28 The term speculatores has undergone changes in meanings and applications over the

years. The speculatores of the first century B.C. are much different from the speculatores which appear on the inscriptions and literature of the 2nd century A.D. For a comprehensive discussion of this subject, see M. Clauss, Untersuchungen zu den Principales des

romischen Heeres von Augustus bis Diokletian: Cornicularii, Speculatores, Frumentarii,

Diss. Bochum 1973.




ploratores gather information through patrols with much less secrecy. It is plausible to assume that the different natures of the missions in this case also entailed differences in composition and mode of operation.

Caesar refers only twice to speculatores in The Gallic War (11,11; V,49), but it is clear that he made extensive use of this intelligence tool. The term appears in The Civil War, but is used differently. This needs to be considered and explained. There is a tendency in modern research to identify speculatio with exploratio, probably because the Greek term skopos is applicable in both senses.29 Yet it does seem from the passage we have been examining that Caesar made a verbal distinction between the mission of the explorator which was carried out by mobile patrols probing in depth, and the activity of the speculator which involved undercover spying, observation and listening. At the same time, it would be foolhardy to extrapolate far-reaching conclusions from one passage. The connection between the task and the body which carries it out is not always strictly defined, and the question also arises whether the distinction between two types of activity can prove a distinction between two unit types. Here, the picture is much less clear.30

In 54 B.C., Caesar was on his way with 7,000 men to relieve Quintus Cicero who was being besieged by the Nervii. Upon his imminent arrival, the Gauls turned to meet him, and thereby raised the siege. Caesar set up camp and "Meanwhile, by scouts (speculatores) despatched in all directions, he sought (explorat) to find the most convenient route by which to cross the valley" (B.G. V,49).

Caesar used speculatores to find a path, and not, as one would have expected, exploratores. The verb used in defining the mission is explorare, searching and patrolling. Could this have been a secret mission which required the skill of speculatores?3t Caesar's position was clearly inferior to that of the Gauls, and he would have wanted to disguise his intentions; but this does not necessarily mean that he would have used spies in the usual sense of the word.

29 The Latin dictionary of Lewis and Short translates exploratores as: "spy or scout" and speculatores as "eclaireur, scout, spy, looker out." The Latin verb speculari means "to watch, look out, spy out, to watch." The Greek dictionary of Liddle and Scott translates the word skopoi as equivalent to exploratores and speculatores.

30 Gichon, "Intelligence" (cit. n. 1), p. 137 attempts, on the basis of a linguistic observation, to claim that there is a distinction in the "type of action". It is not attested in the text. Sheldon (cit. n. 1), p. 108, assumed, on the base of a later inscription that there were 10 speculatores in each legion. However, there is no evidence of this in Caesar's writings, and as mentioned, there is no proof of the establishment of a regular unit by him. Caution must be used with the analogy to the later speculatores, where most of the evidence about them is mainly from inscriptions, which are from the end of the 2nd century A.D. For a discussion on the speculatores of the legion, see A. Domaszewski, "Zur Geschichte der romischen Provinzialverwaltung", Rhein Mus. Phil., 45, 1890, 2 ff.

31 Such for example claims Sheldon (cit. n. 1), p. 108.



82 AMIRAM Ezov

The mission was to find paths of access, and one would have expected exploratores to be used, by their very nature and training. It would seem, then, that there is a lack of verbal distinction between speculatores and exploratores and

that secrecy cannot be regarded as the feature which marks one off from the

other, either as to their type or to their function. At the same time, one might

speculate - no more than that - that speculatores is used here to refer to individuals and not to a unit, and does not refer here to a spying mission at all.

M. Sheldon claims that, despite the general tendency to translate speculatores as "spies", their main role was to deliver litterae to Rome and from one

camp to another.32 This claim cannot be proved from the text of The Gallic War, but it gains some support from The African War, where it is stated that Caesar in

praetorio sedens per speculatores et nuntios imperabat quaefieri volebat (B.A.

31,4). It is not necessary, however, to infer from this that the speculatores served as messengers. The line may be interpreted to mean that Caesar was able to make decisions while sitting in his head-quarters on the basis of information which came to him from speculatores, and issued instructions which he sent out with nuntii, his messengers. There is a clear distinction in the passage between

nuntii and speculatores, and it is only reasonable to suppose that the second term refers to a different activity. It is true that in Imperial times, the speculatores were, amongst other things, attached to the staff of provincial governors, and it is possible that Caesar also used speculatores as a sort of command

detachment.33 Yet even if we accept that in this passage they are to be under-

stood as staff messengers, it is doubtful whether this interpretation could be

imposed on The Gallic War. The references to letter-bearers there indicate that

they were mostly natives, or, in one case, a slave persuaded by his Gallic master

to deliver a message (B.G. V,45). Earlier, when Quintus Cicero wished to send despatches to Caesar, he was compelled to promise large rewards to the mes-

sengers (B.G. V,40). The conclusion must be that there was no regular signal unit. On the contrary, judging by Cicero's promises of rewards, the messengers seem to have been volunteers. When Caesar reached the territory of the Nervii

and learnt from prisoners what was happening in Cicero' s camp, he persuaded a

Gallic horseman with large rewards to take a message. "The letter he sent

written in Greek characters, lest by intercepting it the enemy might get to know

32 See Sheldon (cit. n. 1), 106 which refers to VII,90; IV,38; 11,35 and brings as an example

without any basis the letters which Labienus sent to Caesar during the Belgian rebellion

of 57 (B.G. II, 1). 33 For a view of the speculatores as "relaying commands" see F. Lammert, R.E. 3 A, 2,

1929, s.v. speculatores, col. 1583. For the function of the speculatores in the officium, see

also Domaszewski (op.cit. n. 30), p. 203. Used in the framework of battalion reconnais-

sance as "control units" of the commander, they are also customary in the Israel Defense

Force.




of our designs" (B.G. V,48). In the other places where messengers are referred to there is no mention of their identity.34

Another claim by Sheldon, that the speculatores gathered information on potential plots, and that they are most likely the source to which Caesar refers in expressions such as "persistent rumours were received" or "it was reported" (e.g. B.G. I,7), is no more than a reasonable supposition.35

From the limited references to speculatores in The Gallic War we obtain two main functions:

1. Spying, or listening in on the enemy camp. 2. Patrolling, probably by individuals. Despite the partial overlapping of functions with the exploratores, there

appears to be a distinction between the two units which took part in the incident, a distinction which does not apply in B.G. V,49, where the speculatores performed a routine patrol mission. It is possible that Caesar distinguished between the units only when referring in a particular operation to two distinct bodies performing distinct tasks, in which case the distinction is based more on the type of operation than on the type of unit. As we have seen, it is impossible to attribute to the speculatores a type of operation essentially different from any included in the general term of patrol activities. At the same time, the exploratores are never described as spies, and it appears that the operatives in any spying mission were called speculatores.36

We have no evidence for the consistent use of speculatores as despatch carriers in The Gallic War. Our analysis has shown that the speculatores were under the command of the general for various missions, one of which would have been to pass orders from the general to his units, a task which the exploratores could also fulfil. It is certainly going too far to assert that this was their main function.37

There is no reference in the sources to the number or organization of the speculatores, but it seems likely that they were few and operated on an individual basis. The evidence from The Gallic War for the function of the speculatores is very patchy, and requires supplementation from The Civil War, where there are relatively numerous references to the subject.

34 A certain strengthening of the "messenger" thesis can be found in a remark by Suetonius (Caligula, 44) which describes the reasons for sending Gaius's letter to Rome: monitis speculatoribus, ut vehiculo ad forum usque et curiam pertenderent. The letter was delivered to Rome by the speculatores. However, it is doubtful to conclude that this was their main function. Their vicinity to the praetorium made them available for various duties where secrecy was important.

35 Sheldon (cit. n. 1), p. 108. 36 The only source where exploratores appear as spies is Frontinus, Strat. IV,7,7. 37 This is Sheldon's claim (cit. n. 1), p. 106.



84 AMIRAM Ezov

III. Intelligence failures

Caesar's intelligence was not without its failures and blunders. In 57 B.C., during the campaign against the Nervii, Caesar had neglected to throw out a screen of patrols during the construction of a camp, before the arrival of the main force. The cavalry accompanying the baggage train failed to detect an enemy ambush, and Caesar was required to put up a hasty defence against the surprise attack launched by the Nervii (B.G. II,19ff.). Furthermore, we have already seen in other places (e.g., B.G. II,16) that the enemy's approach is revealed to Caesar through external intelligence sources (prisoners and deserters) while one would have expected this information to be supplied by patrol units operating according to routine battle procedure.

The quality of information obtained on the eve of the incursion into Britain may be seen as a failure, even if it is not completely clear what Volusenus' specific objectives were. The first failure is in the source of information utilized, and the second failure must be the sort of information supplied by this source. At any rate, Caesar explicitly states that his soldiers were surprised by the enemy's mode of fighting, and the information concerning access to the mainland was defective (B.G. IV,25).

The great rebellion instigated by Vercingetorix and the Arverni in 52 B.C. took Caesar by surprise. This is apparent from the lack of Roman response to the first stages of the rebellion and the Gauls' success. Despite the account of secret gatherings which were said to have been held before the rebellion, Caesar had no prior knowledge of preparations since he carried out his original inten- tion of travelling to Italy to hold the assizes (B.G. VII,l). First reports of the rebellion reached him there, and his unreadiness is apparent from his immediate problem, how to reach his army (B.G. VII,6).

IV. The influence of intelligence on Caesar's war plans in The Gallic War

Caesar's utilization of intelligence in the field is a reflection of his person- ality and skill as a general. His military celeritas, his talent for exploiting opportunities and tactical weak-points, his need to improvise against a numeri- cally superior but politically incoherent opponent, his movement over vast tracts of unfamiliar territory, all required prior knowledge of the enemy's circumstances. The information obtained formed the basis for Caesar's situation assessments, his reactions, his operations and his battle plans. One example which we have already dealt with at length is that of the Belgian withdrawal from their camp at night. It is true that, at first, Caesar reacted hesitantly, but as soon as the reports were verified and clarified he sent his cavalry off to delay the rearguard and despatched three legions after them to force a decisive battle




(B.G. 11,12). In another instance, it was the information supplied by the exploratores concerning the movement of the Helvetii across the Arar (Saone) which led to the planning of a night surprise attack (B.G. I,12). During the siege of Gergovia, it was topographical information on weak-points in the defence, supplied by deserters and exploratores, which helped Caesar evolve an elabo- rate deception which led to the fall of the town (B.G. VII,44).38 During the incursion into Britain, it was after receiving information from deserters and prisoners concerning the ford across the Thames that "Caesar sent the cavalry in advance and ordered the legions to follow up instantly" (B. G. V, 18).

Intelligence also served to prepare soldiers for coming events, and in- creased their preparedness for battle on a psychological level. During the campaign against Correus, chief of the Bellovaci, in 51 B.C., Caesar learnt from prisoners of a planned ambush against his foragers. Hirtius says: "The enemy's design was found out, and our men, with hearts and hands all ready for fight -

for with the legions supporting they had no idea of declining battle - reached the spot troop by troop" (B.G. VIII,18).

In as much as our interpretation is correct, the following passage taken from one of the episodes in the civil war illustrates Caesar's skilful use of his intelligence arms:

"As for the rest of the cavalry, they too had their orders - to be ready at hand, equipped and armed, each man in his proper place. These orders, however, he did not issue personally on the spot, surveying the situation from the rampart; but so remarkable was his skill and knowledge of warfare that, making use of look-outs and orderlies, he issued the instructions necessary for his purpose as he sat in his head-quarters" (B.A. 31,4).

V. Exploratores and speculatores in The Civil War

The military report De Bello Civili differs in character and purpose from De

Bello Gallico.39 The Civil War is itself part of Caesar's attempt to legitimize his

position and his war against the citizens of Rome. It is in great part an exercise in propaganda. The two works, De Bello Africo and De Bello Hispaniensi, were not written by Caesar.40 It is therefore impossible to trace the development of

38 An additional example: Caninius uses the information which the scouts brought to him to trap the enemy's grain transporters (VIII,35).

39 For discussion of the text and the purpose of the composition, see J.M.Carter, Julius Caesar - The Civil War, Warminster 1991, p. 16; see also J.H. Collins, "Caesar as Political Propagandist", ANRWI 1, 1972, p.945.

40 Collins (cit. n. 39), p. 945. The identity of the writers of The African War and The Spanish War is not known. Suetonius (D.J. 56) writes: "The question of who wrote the books on

the war in Alexandria in Africa and in Spain is still in doubt." See also M. Geizer, Caesar, Oxford 1969, p. 251.



86 AMIRAM Ezov

Caesar's own linguistic usage during these later campaigns, and it is regrettable that we cannot compare his terminology here with his terminology in The Gallic War. What is open to comparison, however, is the mode and scope of operations of the various intelligence arms in the two periods. Just as in the Gallic campaigns, Caesar operated both the exploratores and the speculatores for scouting and spying missions.

Another particular intelligence source which was of great value in the civil war was afforded by "deserters" (perfugae) of high rank, who defected from one camp to the other on the eve of battle. These men had many invaluable and detailed pieces of information concerning the enemy's plans and dispositions. In Africa, in 47 B.C. at Ruspina, a great number of men of all ranks defected to Caesar, and the enemy's plans were made known to him (B.A. 35). On the eve of the battle of Munda in Spain, in 45 B.C., the military tribune, Q. Marcius, with another horseman, defected. The information they brought with them was checked and verified by other prisoners (B.H. 11).

The flow of defectors between camps was two-directional as the following passage shows:

"When Pompeius got to know from deserters (ex perfugis) that the surren- der of the town had taken place, he moved his camp towards Ucubi, built forts at intervals in that locality, and proceeded to keep within his emplace- ments. Caesar struck his camp and moved it closer to that of Pompeius. It was at this same time that early in the morning one of the heavy-armed troops from a native legion (loricatus unus ex legione vernacula) deserted to us and reported that Pompeius had assembled the inhabitants of the town of Ucubi and given them orders..." (B.H. 20).

The information which the defectors could supply was of a particularly high quality since it was internal, and was unique in providing mental and psychological insights concerning the state of the enemy, such as the attitude and morale of the troops.

The numbers of defectors willing to provide information reduced the need for intelligence from prisoners. Instead, Caesar strove to recruit these into his own army, and preferred to see them as "colleagues" rather than prisoners of war. When the occasion demanded, however, he would extract information from prisoners which would otherwise have been unobtainable. On the eve of the battle of Ilerda, in 49 B.C., Caesar's cavalry captured some waterbearers who revealed that the enemy was secretly striking camp. On hearing this, Caesar ordered his own camp to be struck. This reaction pressured the enemy into cancelling their planned night march (B.C. 1,66).

The cavalry in the civil war performed roles similar to those they carried out in the Gallic war: defending the legion's flanks, pursuing the enemy in retreat, and gathering intelligence. The horsemen who captured the foragers




must have been on one such intelligence mission (B. C. 1,66). Caesar routinely used the cavalry as a skirmish screen. When, for example, he first fought at Ruspina in Africa, in 47 B.C., he sent forward a horse patrol to secure the front and to locate the enemy (B.A. 12). Later in the same campaign, Caesar was unaware of an enemy ambush near Uzitta, but the cavalry screen he had sent ahead threw the enemy into confusion and foiled the attempt (B.A. 50). The Pompeians themselves testify to the efficiency of Caesar's cavalry. During the Ilerda campaign, high-ranking officers in Pompeius' army "pointed out that Caesar's horsemen poured around at night and beset every place and every path" (B.C. I,67).

1. Exploratores

On the eve of the battle of Ilerda in Spain, in 49 B.C., Caesar had channel dug in order to divert the water of the Sicoris (Segre). Pompeius' commanders, Afranius and Petreius, fearing that their supplies would be cut off when the work was completed, decided to leave the area and move the theatre of operations to Celtiberia where they could expect to recruit auxiliaries from the local inhabitants. Having adopted this plan, they ordered all the boats along the Ebro to be commandeered and assembled at the town of Octogesa on the Ebro, some thirty (or twenty) miles from Caesar's camp.41 At this point of the Ebro they ordered a bridge of boats built. Then they transferred two legions across the Sicoris at Ilerda and built a camp (B.C. 1,61). Caesar remarks, "When this was ascertained by means of scouts (per exploratores), Caesar [continued] day and night his task of diverting the stream by the utmost efforts of his soldiery..." (1,62). The passage tells us that the mission of the exploratores was to track the enemy. The exploratores moved with the enemy and perhaps up to thirty kilometres abead of them, to find the location of the bridge over the Ebro; and it is this intelligence report and the news concerning the beginning of the withdrawal of the Pompeian forces from Ilerda which persuades Caesar to send his cavalry to thwart the move. Just as in the Gallic campaigns, the exploratores operate far from the main force, in close touch with the enemy.

Exploratores are also seen to be operating far from the main force in the following example:

"... letters having been sent by Pompeius through all the provinces and communities after the battle at Dyrrhachium, couched in a more exaggera- ted and inflated style than the facts warranted, a report had spread abroad that Caesar had been beaten and was in flight with the loss of nearly all his

41 On the place of Octogesa and the distance from Ilerda, see the discussion in Carter (cit. n. 39), p. 200.



88 AMIRAM Ezov

forces. This rumour had made the routes full of danger, and was drawing off some of the communities from their friendship with him. In consequence of this it happened that persons sent by various routes from Caesar to Domiti- us and from Domitius to Caesar could by no means finish their journey. But the Allobroges ... having seen on the route some scouts (exploratores) of Domitius, either by reason of their old intimacy because they had waged war together in Gaul, or in the elation of vainglory, set before them everything that had happened, and told them of the departure of Caesar and the arrival of Pompeius" (B.C. 111,79).

From the story it transpires that exploratores operated here as a matter of course in pathfinding ahead of the main force. We should also note that the exploratores in the story are some of those who were sent out by many routes (pluribus dimissi itineribus). If all the dimissi were exploratores, it would appear that exploratores were the messengers attempting to maintain communi- cations between Caesar and Domitius.

The passage also hints at the origin of these particular exploratores. The Allobroges knew them from the Gallic war. This may perhaps confirm our earlier conclusion, that Caesar used as exploratores members of local Gallic tribes. The Allobroges' prior acquaintance with them would not then be surpris- ing.42 Caesar was not the only one to use exploratores in the battle of Dyrrha- chium, however. Pompeius used exploratores on the eve of battle. He is said to have failed to understand Caesar's intentions, thinking that he was leaving the field of battle due to a lack of supplies. Only after he had received information per exploratores did he understand Caesar's motives, and move his camp toward Dyrrhachium.43

In 48 B.C., on the Thessalian plains of Pharsalus, Plutarch tells us that "...

the scouts (skopoi) came in with a report that they saw many shields moving to and fro in the enemy's camp, and that there was a noisy movement there of men coming out to do battle. After these, others came announcing that the foremost ranks were already forming in battle array" (Plutarch, Pompey 68.3). It is worth noting that after the "lookouts" came "others" who reported that the first soldiers were already in position for battle." In other words, the skopoi were not the only intelligence source. The passage expressly states that the skopoi were within hearing range of the enemy camp, about six kilometres away from Caesar's own.45 The very proximity of the camps required concealed or camou- flaged movement.

42 On the Allobroges, see B.C. 111,59. 43 B. C. III,4 1. 44 According to the context, although it would be possible to translate skopoi as speculato-

res, apparently here exploratores are meant.

45 Compare Plut., Caesar 44. On the Battle of Pharsalus, see C.B.R. Pelling, "Pharsalus",

Historia, 22, 1973, 249.




Altogether, there are few references to exploratores in The Civil War. The scarcity may theoretically be due to the rare use made of them, but it is more likely due to the wide use of the term speculatores. It is possible, as we shall see below, that the terms did not characterize well-defined units, and that, in fact, Caesar did not distinguish between them when referring to the activities of a patrol unit. The missions of the exploratores in The Civil War appear to include tailing, observing, listening and spying with a view to assessing and discover- ing the plans and movements of the enemy. Perhaps this is why the border between exploratores and speculatores, not previously established anyway, is ill-defined here.

2. Speculatores

The speculatores appear more frequently in The Civil War, in relation both to their own showing in The Gallic War, and to that of the exploratores here. Does this signify a change in their objectives and mode of operation?

In the two extracts from The African War (B.A. 31 and 37 - on the eve of the battle of Ruspina) already dealt with above from a different perspective, we see clearly that the speculatores are attached and readily available to Caesar personally. We have already been inclined to interpret the speculatores of the first passage as intelligence gatherers rather than messengers transmitting commands. Whatever the correct interpretation might be, there can be no doubt that the speculatores were close to the general's table, served as direct communication between him and his subordinate units, and perhaps, if we accept the interpretation suggested above, were his eyes in the field, to the extent that he could issue the necessary orders from inside his praetorium. The second passage strengthens this hypothesis: "On January 25, at approximately the first watch, he personally issued orders that all his scouts and aides-de-camp should hold themselves at his disposal" (B.A. 37). Some see in this passage Caesar treating the speculatores as an existing, well-defined body. But the text, im- perat speculatores apparitoresque omnes ut sibi praesto essent, points no more to a definite unit than to a simple ad hoc detachment.46 The language used here does not, then, tell us anything about the character of the unit. What is clear, however, is that the speculatores are once more a direct tool of command between Caesar and events on the ground, whether as the conveyors of commands, according to one theory, or as scouts participating in the general organization leading up to the battle, according to the interpretation offered here. In order to confirm or reject either interpretation, we must examine the use of speculatores in other passages where they are mentioned.

46 The apparitores were "servants", esp. public servants, hence assistants to authorized persons.



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On the eve of the battle of Dyrrhachium, "When this entrenchment was finished it was noticed by Caesar's scouts (speculatores) that certain cohorts, enough to seem equivalent to a legion, were behind the wood and were being led to the old camp" (B.C. III,66,1).

"The scouts reported to Caesar (speculatores Caesari renuntiarunt) that the

standards of the legion had been borne thither. They assured him that the same thing had been seen from some of the higher redoubts" (B.C. III,67, 1).

An analysis of these passages reveals that the mission of the speculatores was essentially that of patrolling and tracking the movement of the enemy, about nine kilometres from Caesar's camp. This is not a spying mission, but one of observing or listening to the enemy camp, as part of Caesar's security screen and intelligence gathering operation on the enemy's movements. The speculatores have a similar mission on the eve of the battle of Munda in 45 B.C. "Scouts (speculatores) came back with the news that Pompeius had been in

battle formation since the third watch. On receipt of this news Caesar displayed the flag-signal for action (Hoc nuntio allato, vexillum proposuit)" (B.H. 28). It is true that this passage does not show whether we are dealing with scouts or with spies, but the speculatores are operating far from the main force on a

mission to locate enemy movements. A passage from the Ruspina campaign reveals the position of the specula-

tores in the order of march:

"Meanwhile, when Caesar had now advanced about three miles from his camp, information obtained by his scouts and mounted patrols (per specu-

latores et antecessores equites) reached him that the enemy's forces had

been sighted by them at no great distance. And indeed simultaneously with that information they began to see a great cloud of dust" (B.A. 12).

There is a striking resemblance between the position of the speculatores in

the order of march here, and that of the exploratores in The Gallic War. It is worth noting that in this instance the speculatores were not operating far from the main force, given the appearance of the enemy with the delivery of the

information. That the exploratores are not mentioned during a mission where

one would have expected them to be mentioned, since it was performed by them

in Gaul, increases the suspicion that Caesar was using vague terminology here, indicating that the word was not used for a well-defined unit. The translation

"6scouts" is applicable in this case both to exploratores and to speculatores. At

the same time, it is worth noting that there is a distinction between the speculatores and the mounted advance guard (antecessores equites), each with a

different mission: one, to gather intelligence, the other, to secure the head of the

column. This is also seen in the following passage (45 B.C.):

"Pompeius (the Younger) took to flight with a few companions and occu-

pied a certain spot which possessed natural defences. When the cavalry and




infantry cohorts which had been despatched in his pursuit learned of this from scouts (speculatores) they had sent on ahead, they pushed on day and night" (B.H. 38).

Here, it is explicitly stated that the speculatores were already ahead before other troops were sent to pursue the enemy. The mission was clearly one of patrol and not of spying, and similar in every respect to one of the tasks of the exploratores. Is this the only function the speculatores had?

References to spying missions conducted by speculatores as individuals are infrequent, but in one such episode it is related that "One of the Lusitanians who had been despatched from his escort (praesidium) on reconnaissance in accord- ance with normal military routine was now spotted by the Caesarian force, and Pompeius was promptly surrounded by the cavalry and cohorts" (B.H. 38 - following Hoffman's conjectural emendation of the text). We learn here in an aside that it was an army custom (more militari) to send spies from the commander's praesidium, that is, it was a routine military procedure. In another instance, during the Spanish campaign (46-5 B.C.), when Pompeius the Young- er had disposed his forces by the river Salsum, skirmishes broke out between the forward troops and cavalry of both sides on their outworks (in statione). During these exchanges, a "spy (speculator) from the Second legion, on Pom- peius' side" was captured and executed (B.H. 13).47 There is no doubt that this speculator was on a spying mission and that he was an individual attached organically to a legion. The nature of his mission is also indicated by the nature of the sentence passed upon him. Unlike other prisoners, captured spies were summarily tried and executed.48 This may be illustrated by the following account: "That night some scouts (speculatores ) were caught - three slaves and one soldier from a native legion. The slaves were crucified, the soldier behead- ed" (B.H. 20).49 This passage slightly broadens our knowledge concerning the status and origin of speculatores. The spies in this case were not regular soldiers, but slaves or soldiers who had been selected because of specific qualities suitable for the mission. While all the speculatores were executed, as opposed to the fate of other prisoners, the soldier received preferential treat- ment, being of higher social status. The speculatores, then, were socially heterogeneous, being composed of slaves, legionaries and (e.g. B.H. 38, dis- cussed above) local inhabitants. Two Gaetulians, as another example, were sent by the Pompeian general, Scipio, to spy (speculandi gratia) on Caesar; but they

47 Here is an interesting intelligence item: "And at the same time a 'ball' was sent with the inscription: 'On the day you advance to capture the town I shall lay down my shield'." This piece testifies to the internal intelligence sources of Caesar in Pompey's camp.

48 On the verdict of spies, see Digest, 48,16,16. 49 On the legion Vernacula of Pompey, see Keppie (cit. n. 13), 141.



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gave themselves up harmlessly (B.A. 35). Their mission, incidentally, was to see whether there were any obstacles in the way of the elephants in front of the camp or the rampart gates, and at the same time uncover Caesar's battle dispositions and tactics. It should be noted that the mission was imposed on only two men which may be an indication of how the speculatores operated. It is worth pointing out that spying missions were given to local inhabitants in exchange for material rewards, from which we may infer that there was no regular unit for the job; otherwise, there would have been no need to persuade individuals.50

The references to the origins of speculatores are not numerous, and gener- alizations should not be made from those passages which mention in passing the particular origin of a speculator. Even so, the various passages do seem to indicate a preference for local inhabitants for spying missions in or near the enemy camp, probably because of their familiarity with the territory and the language, and their ability to go undetected precisely because they were locals.

Speculatores: Conclusions

1. The term speculatores appears throughout the whole period of the civil war in various theatres of operation for a whole list of activities whose common denominator is field intelligence, in Caesar's army and in those of his rivals. The frequent and continuous references might tempt one into concluding that the speculatores were a regular unit of the legion, but we do not in fact have enough evidence to assert this. We do not really know how they fitted into the battle dispositions.

2. Our discussion has revealed that the term speculatores was used for soldiers involved in a wide range of intelligence missions, including patrolling, observation, tracking the enemy, serving as advance guard, and spying. There is much similarity between their activity and that of the exploratores in The Gallic War, and there is more than a "faint suspicion" that Caesar often failed to

distinguish between the two when referring to soldiers carrying out certain of

these intelligence missions. The lack of distinction is all the more marked in

Greek, where the term skopoi is used for both in the writings of Plutarch. A

clear distinction between the two terms is made only in The Gallic War (B.G. 11,1 1), where Caesar needed to describe two different activities and two differ-

ent bodies of men. Yet, already in The Gallic War, the speculatores are to be

50 "... and so thrown into no little panic as a result of his forbearance, they chose from the

Gaetulians two men whom they considered to be the staunchest supporters of their cause,

and after offering them large rewards and making them generous promises sent them in

the guise of deserters on a spying mission into Caesar's camp" (B.A. 35).




seen looking for paths in rough terrain, an activity which is by definition a scouting mission (B.G. V,49). This strengthens the hypothesis that at this stage there were not as yet regular and clearly defined intelligence units, but individuals or a body assigned ad hoc to a particular mission because of their suitabil- ity. The characteristic most in demand would have been the individual's origin, but other characteristics looked for would have included courage, resourceful- ness and observation skills. The impression is, however, that Caesar preferred to use the term exploratores to describe those engaged in scouting, observation or listening of a more structured nature. This does not contradict the previous statements. The structured nature is best shown by the fact that commanders, normally centurions, were appointed according to the type of mission. Caesar never uses exploratores to describe those engaged in spying, for whom he reserves the exclusive term speculatores.

3. The speculatores were under the general's direct orders, serving as tools of command, overseeing, communication and intelligence gathering. The proximity of the speculatores to the praesidium and later to the officium of the commander is one of the later features of the legionary speculatores in the second and third centuries A.D. when they were no longer in this line of work.

4. In the few places where the origin of speculatores is mentioned, particularly when concerned with spying missions, the speculatores usually turn out to be locals. At the same time, they were not all of the same social status. Some were soldiers, mostly from "native" legions, and others were slaves or allies. It would be going to far to impose this social division on all the speculatores in their wide range of tasks.

VI. Conclusions

1. Exploratores and speculatores in Caesar's army were not separate inde- pendent units within the legion. They should be seen, basically, as forces, usually from the cavalry, assigned for ad hoc intelligence missions ranging from deep probes by patrols to spying operations by individuals.

2. Caesar usually used the term exploratores to indicate a unit on a patrol mission, and speculatores to indicate individuals on a spying mission. The two terms were not technical, however, and we have seen many instances where speculatores has been used in preference to exploratores.

3. Caesar was not a tactical innovator, nor was he known for methodical logistical preparations on the eve of battle.5' He relied on his tactical skill, and on his ability to improvise when difficult situations and military challenges required solutions. Even so, despite a few outstanding failures of intelligence,

51 See J.F.C. Fuller, Julius Caesar: Man, Soldier and Tyrant, London 1965, p. 316.



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he made great use of his various intelligence arms enabling him to make a situation assessment before forming a battle plan. As Napoleon wrote, "In the art of war, as in mechanics, it is time which decides between mass and force."52 In other words, speed increases mass, and this formula is at the heart of tactical surprise. Caesar made up for his relative neglect of preparations for battle by speed in manouevre and his tactical ability in the field. It was his relatively skilled use of field intelligence which allowed the conditions for multiplying mass by speed.

Kibbutz Mishmar Haemek, Israel Amiram Ezov

52 Cited from Fuller (cit. n. 51), p. 322.



Documents

Source: Historia: Zeitschrift für Alte Geschichte, Bd. 45 ... · THE "MISSING DIMENSION" OF C. JULIUS CAESAR Julius Caesar opens his commentaries on the Gallic War with the famous