9

Roman military intelligence

As earlier chapters have shown, simple lookouts, spies, and messengers are spoken of in Livy as operating in very early times. The Latin words speculator and explorator were originally translated as lookout, spy, scout or explorer, and seem to have been interchangeable.¹ Already in the works of Caesar, Sallust, and Cicero these men begin to take on the duties they would perform in imperial times.² As the Roman Army grew larger, more sophisticated, and more professional, scouts took on separate and distinctive duties. The exploratores became cavalry scouts, while speculatores became intelligence couriers and clandestine agents. Unfortunately, many scholars continue to use them as interchangeable terms, and part of the confusion comes from the Greek sources, for example Dionysius of Halicarnassus, where the word for spy, kataskopos, is used for both.³ There is a basic difference, however, between scouting by mobile reconnaissance forces in depth and observation done from static listening posts.⁴ Exploratores were sent out in strength on specific missions. They were to locate the enemy and report on its actions. The intelligence gained would be used to prevent a surprise attack – a situation always to be avoided. The intelligence could also be a basis for planning, and perhaps surprising the enemy. Another task for the exploratores was to locate a far-away enemy and reconnoiter the ground and the best approaches to its positions. Speculatores, on the other hand, worked in small numbers, some times in pairs or even alone on clandestine missions at night to observe the enemy. They did this from observation posts that were set up when the forces had drawn near to one another and which remained relatively static, as on the eve of battle.⁵

Unfortunately for us, although Caesar is our best source on these matters, he does not indicate how or when these formal organizations came about.⁶ We do not even know whether his units of exploratores and speculatores were permanent special intelligence units, or whether he chose his intelligence people from regular formations on the line. If he did, then we must conclude that it was only during the professionalization of the army under Augustus that these institutions became permanent. In their magisterial work on Greek and Roman warfare, Kromayer and Veith even notice how much slower the Romans were in developing their intelligence section as opposed to other parts of their army.⁷ But finally, during the Augustan reorganization of the Roman Army, the speculatores and the exploratores both become an institutionalized part of the Roman military and we can trace their participation in Roman intelligence activities throughout the Empire.

Speculatores

Although Caesar only mentions speculatores twice in his Gallic War, it is clear that during the period of the civil wars these men continued to be used as couriers and spies by both sides. A speculator spying for Gnaeus Pompeius, son of Pompey, was captured by Caesar’s troops and put to death.⁸ The itinerant executioners who killed all the men proscribed by the triumvirs were speculatores. We know Marc Antony formed his speculatores into a special cohort, because they are commemorated on one of his coins. Examination of the Caesarian accounts shows the speculatores working in small numbers, sometimes even as pairs or as individuals.⁹

It is not surprising, then, that Augustus formalized this useful arm of the Roman military. Many of his reforms revolved around providing Rome with better communications. We have already seen this in his establishment of the cursus publicus. Another military reform inaugurated by Augustus which benefited the transmission of intelligence was the reorganization of the Mediterranean fleets. These fleets were used, in general, for military assistance and for the swift dispatch of letters and orders. Several times during the second century ad, detachments of Italian squadrons were stationed at Seleucia in Syria, undoubtedly to facilitate communications. On the Italian end, there were naval runners from Puteoli and Ostia to Rome, where both flotillas had separate barracks for their respective personnel.¹⁰

Just designing the infrastructure of a communications system was not enough; Augustus also had to man it. His military reforms included changing the internal structure of the legion to provide the personnel who would carry the intelligence along these newly established networks. Under Augustus, each legion normally incorporated its own subunit of ten speculatores, acting as scouts, messengers, and collectors of military intelligence.¹¹ They worked in regular infantry units, auxiliary regiments, and in units of explorationes.¹²

An important fact to remember about early Roman imperial intelligence activities is that they were performed by a wide variety of individuals, whose functions overlapped. Men with several different titles might be called upon to act as police officials, military intelligence officers, couriers, or agents provocateurs,¹³ The speculatores acquired in imperial times diverse, semicovert, and fully secret activities that demanded special trust, not unlike military field security, which in most modem armies is in one way or another affiliated with military intelligence.¹⁴ Early emperors employed the Praetorian Guard, especially its centurions and tribunes, as plain-clothes men to arrest those accused of treason.¹⁵ Scholars have assumed that the men chosen for such missions of trust belonged to military intelligence.¹⁶

Use of the speculatores was not limited to the emperor. Provincial governors, too, used speculatores on similar missions. An inscription now in London records a group of speculatores seconded to the governor’s staff from the Second Augustan Legion.¹⁷ One famous example of a speculator employed as a courier comes from the Gospel of Mark: Herod sent a speculator to the prison with an order to execute John the Baptist.¹⁸ Finally, speculatores acted as police to ensure the collection of debts and taxes.¹⁹

The three praetorian cohorts in the capital served as the emperor’s bodyguard, but as this was an unwieldy group of 1,500 men, within the ranks of the guard there emerged a special inner corps of mounted speculatores. Thus the legionary speculatores were not the only military personnel performing intelligence and security functions. This new group called themselves “speculatores of Caesar” and, being mounted, they were, in effect, a special reserve of the guard’s cavalry squadrons. They served as the emperor’s bodyguard, and this arrangement no doubt began with Augustus. He is recorded at least once as having stayed in the country home of one of his speculatores, and to have reciprocated the hospitality.²⁰ These particular praetorians were chosen for their impressive physiques and their principle task was to protect the emperor from assassination. Mounted speculatores of the Praetorian Guard were also employed, like their legionary counterparts, to convey messages and dispatches, and the provision of information, secret or otherwise, to the emperor. There is reason to believe that they were engaged in undercover activities such as espionage, arrests, taking suspects and detainees into custody, and the execution of condemned men.²¹ The extent to which Augustus, like his successors, employed praetorian speculatores to conduct and organize potentially sinister activities is uncertain, but it is not improbable that it was one of the services that he required of them. This was certainly the case in later years, but Augustus’s reign also saw its share of undercover operations related to internal security. There seems to have been a difficulty in maintaining a clear division between external intelligence and internal subversion. The danger was always present that a ruler would use the speculatores for political purposes.

Legionary speculatores continued to be used throughout the empire. These men, along with their Praetorian counterparts, were couriers for all sorts of intelligence.²² Suetonius and Tacitus mention their use as special couriers for the transmission of information in highly delicate and volatile situations. In ad 37, when a doctor assured the praetorian prefect, Macro, that Tiberius would be dead in two days, he sent his speculatores to warn imperial governors and army commanders.²³ It was through speculatores that Vitellius received the news from Syria and Judaea that the East had sworn allegiance to him.²⁴ During that same hectic year, ad 69, there was a spate of activity by speculatores, as four different emperors, Galba, Otho, Vitellius, and Vespasian, occupied the throne. Otho used one of his freedmen to bribe “the officer of the password” of the praetorian speculatores, in an attempt to tamper with the loyalty of the entire corps. He was successful, and it was the corps of speculatores that hailed him as emperor and who protected him. But it also was a speculator who later killed Galba.²⁵

Claudius was accustomed to having a few speculatores standing by when he attended dinner parties.²⁶ Josephus’s descriptions of the line of march that followed Vespasian and Titus during their Palestine campaigns indicate that a general’s guard was comprised of speculatores.²⁷ Records show that a detachment of speculatores was regularly assigned to a general’s headquarters.²⁸ They served in auxiliary regiments like the speculatores quartered in the two forts in the El Kantara defile in Algeria.²⁹ They are described as running “independent communications networks” capable of gathering and transmitting intelligence on the North African frontier and the troops were quartered in the burgi speculatorum by the watchtowers.³⁰

There are two brief references to speculatores being the bodyguards of Galba and Otho.³¹ During most of the Flavian period speculatores seem to have served as the palace guard; this assumption is supported by an inscription of ad 76 concerning veterans’ privileges, as the speculatores are set apart from the other praetorians.³² The praetorian prefect was in a very powerful and dangerous position. He held the emperor’s personal safety in his own hands. He had at his disposal an elite body of troops in and near the capital itself, as well as the speculatores who could act as his personal agents. He played a central role in the innermost councils of the emperor, and was privy to his most intimate confidences. The speculatores were well placed to keep an eye on the emperor’s correspondence with imperial governors of all the provinces, since his letters to them, and their replies, were carried by speculatores who constituted part of the prefect’s command.³³ The other confidential functions of speculatores, such as espionage, detention, and execution, were likewise performed under the prefect’s direction and added further to his power. The Emperor Trajan (ad 98–117) took steps to increase his personal security measures. Whereas earlier emperors had employed both a German bodyguard and a mounted guard of praetorian speculatores, Galba (ad 69) disbanded the German bodyguard and Trajan stopped relying on his speculatores. Instead, he created a new mounted bodyguard altogether called the equites singulares that assumed that particular function of the speculatores.³⁴ The corps of speculatores was integrated into the praetorian cohorts, and their function as political police was taken over by the frumentarii in the third century.³⁵

The legionary speculatores never lost their primary intelligence function. In the later Empire, we can see them working on Rome’s borders running their own communications network and signaling vital information to the back lines, independent of any regular legionary signals network. Along the southern border in North Africa entire independent units of speculatores were created. Two such units have been identified from inscriptions found in forts near El Kantara in Algeria: the burgus speculatorum Antoninianorum and the burgus Commodianus speculatorius.³⁶ The speculatores in these camps manned the watchtowers that dot the area. Speculatores thus remained Rome’s eyes and ears throughout the Empire, and especially on its borders.

Exploratores

“An army losing contact with its adversary is like a person suddenly attacked by a spell of blindness.”³⁷ Since the Romans did not have electronic listening devices and air reconnaissance, their scouts were their eyes and ears. They sent out strong combat patrols on missions to locate and engage the enemy. These troops had to determine the strength and dispositions of the foe, and take prisoners and interrogate them. Such clashes could become deadly if the enemy’s scouts were out doing the same thing and they discovered one another. Scouts called exploratores were employed in every Roman Army.³⁸ As reconnaissance details, they were at first selected generally from among the regular troops and remained members of their parent units.

Arrian explains the routine procedure of an army on the march: “The mounted exploratores, formed in two combat groups under their own commander, precede the whole army.”³⁹ This division of the scouting screen into two groups is a very sensible arrangement, since one part can be used for the actual routine of scouting while the other may be kept somewhat back and dispatched by the officer in command for other missions. Once the army locates the enemy and engages in battle, these cavalry troops are ranged around the infantry to afford protection. Arrian also tells us that exploratores were sent forward to elevate positions and to observe the enemy.⁴⁰

By the beginning of the second century, exploratores formed a special subunit within each legion. In the Hadrianic period, they are listed in Pseudo-Hyginus as quartered near the first cohort, the equites legionis and the singulares⁴¹ They are thus marked as a special unit at the disposal of the legatus whenever he needed them. This is similar to modern-day combat intelligence and reconnaissance units in batallions and higher formations.⁴² We know the equites legionum did not serve as regular scouts. Their order of march was in the rear near the commander, whom they served as dispatch riders and on special sundry missions.⁴³ Again, according to Pseudo-Hyginus, the exploratores numbered about 65 per legion. Their strength enabled them to carry out all combat intelligence missions, such as reconnoitering in depth, engaging enemy outposts to determine his dispositions, and capturing prisoners for interrogation.⁴⁴

According to Vegetius, a commander chose exploratores personally from the most proven cavalry troops.⁴⁵ A good example was Tiberius Claudius Maximus, a soldier who during Trajan’s Dacian War captured the Dacian king, Decebalus, and cut off his head.⁴⁶ Here is an excellent example of a penetration in depth that resulted in the capture and execution of an enemy leader by a mounted reconnaissance squadron.

Exploratores were given first-class horses to enhance their mobility, as pictorial evidence from the panels on Trajan’s Column in Rome shows (see Illus. 3). They may have had special equipment, but we only know of one item, because of a chance remark by Pliny the Younger, who calls it necessary for exploratores. He mentions a special type of flint stone used to strike fire clandestinely and quickly. We would like to know more about such special equipment, but at least this gives us a glimpse into the exploratores’ activities as they were engaged in forward action behind enemy lines.

Auxiliary units of the Roman Army also needed scouting and reconnaissance capabilities. The auxilia had their own complement of exploratores. The cohort XX Palmyrenorum listed on its rosters in ad 219 more than fifteen exploratores, five of whom were foot scouts.⁴⁷ Then, from the second century onward, we begin to see exploratores as entire units, often numeri under the command of praepositi or praefecti.⁴⁸ They were either infantry or cavalry and were stationed in frontier provinces, usually forward near the border. This system was developed to overcome the evolution of a static border defense all along the empire’s perimeter. Mordechai Gichon has pointed out that “The Limes defenses served… as intelligence gatherers, both by forcing potential enemies to engage them in order to make a hostile penetration and as checkpoints for peaceful passage.”⁴⁹ Elaborate systems of watchtowers, patrol posts, and signal stations (see Chapter 11) could then register the early alert and relay orders and intelligence to troops and headquarters in the rear.⁵⁰

By the reign of Trajan, specific, mobile exploratores units are found, specifically in Rome’s armies in Germany.⁵¹ According to Michael Speidel, these are separate and different from the smaller, lower-ranking explorationes or exploratores units that garrisoned some of the border forts in Germany and North Africa.⁵² By the third century, still another new feature of intelligence collection was introduced that gave a greater measure of sophistication in deploying exploratores along the frontier. The system set up by the Emperor Septimius Severus included strongly garrisoned outpost forts manned by part-mounted cohorts and by units of exploratores. These mobile exploratores units first appear in the beginning of the second century among the troops from Lower Germany who fought in Trajan’s Dacian War in ad 101–106. These troops were not auxiliaries, but rather were selected from legions and attached to expeditionary armies. By the third century, exploratores from Germany are found abroad so often that they may even have become regular members of the emperor’s own field army. Such units appear in Rome’s armies in Germany, and they are known to have participated in campaigns in Dacia, Mauretania, Thrace, Macedonia, and elsewhere.⁵³

Our knowledge of these explorator units is hindered by the fragmentary nature of the evidence and the fact that some of their names are preserved only in shortened version. Gichon, for example, cites the equites sagittarii indigenae stationed at Moahile in the heart of the Negev in advance of the main zone of fortification as just such a unit, whose duties included permanent patrolling, scanning, and, if called upon, guiding and protecting any regular army units in the area.⁵⁴

Speidel has argued that as larger numbers of exploratores were brought together to serve an entire provincial field army, they became mobile units that were administratively autonomous. He believes these large, mobile elite units differed from the smaller, lower-echelon exploratores elements that garrisoned some of the forts along the Upper German Limes (the boundary of the Roman Empire). They were elite troops famous for their fighting power.⁵⁵ The size of these units certainly makes it clear that their task was not limited to the collection of intelligence, but also included long-range patrolling and reconnaissance in force.⁵⁶ For such tasks they had to be mounted and mobile; that is, not confined to the defense of a specific sector of the frontier. Those units that lost their mobility also tended to lose their reconnaissance function.⁵⁷

The garrison location of these exploratores is often the key to understanding how they were deployed. The explorator unit in Mauretania Tingitana was the southernmost camp in the province. In Mauretania Caesariensis, they occupied the farthest outpost in the southwest of the province.⁵⁸ In Raetia, they were the farthest-flung eastern unit in the province that watched over the dangerous Marcomanni.⁵⁹ In Britain, the forts with exploratores were located north of Hadrian’s Wall. In Lower Germany, they were stationed in the bridgehead fort of Divitia, east of the Rhine across from Cologne.⁶⁰ In Upper Germany, the troops were at Niederbieber, again the northernmost unit of the province, also beyond the Rhine. They guarded the northern border against the Franks.⁶¹ The location of these bases thus suggests that the large German exploratores units were assigned the penetration areas outside the Limes, in order to observe native activity. They were a de facto strategic reserve for exploratio. This was the closest thing the Romans had to a “foreign intelligence collection unit.”

Unlike political infiltration, which could be aimed against Parthia or other such civilized, sophisticated courts, surveillance of barbarian tribes was the concern of army units. Large exploratores units watched over tribes, guarded major routes leading into the Empire, and gathered intelligence along the frontiers. The emergence of mobile exploratores units as an elite cavalry strike force was a noteworthy strategic development in the defense of Roman Germany, as by ad 100 free German settlement had moved closer to the border and needed to be watched. The fact that these units were then deployed in other provinces proves that it had been a successful response to increasing pressure on the frontiers. Paradoxically, the very fighting power and mobility of these units, which enhanced both intelligence gathering and the defense of major provinces, may ultimately have led to their premature withdrawal from the frontier in the third century and their absorption into the field army. Thus, when the Emperor Gallienus left Germany for Pannonia in ad 258, he may have taken along the elite exploratores as part of his battle cavalry, thereby leaving Upper Germany unprotected, and it was subsequently overrun.⁶²

The forward stationing of exploratores put them in constant danger of bearing the brunt of a hostile attack, and if they engaged, they were likely to sustain considerable casualties. One way to mitigate these dangers was to quarter speculatores permanently together with other units or near to them. There may have existed permanently combined commands. We know that in Germania Superior they assigned small detachments from the numerus exploratorum to castella on the Limes for lengthy periods of time or even as permanent features. These smaller detachments were called explorationes.⁶³

Scouting in the late Empire is mentioned by Greek writers such as Zosimus and Procopius.⁶⁴ However, in Greek texts, the word kataskopoi (spies) may be applied to scouts, scouting units or troops of the line on scouting missions. The increasing use of cavalry entailed its employment in scouting missions, the more so when fighting horse-borne barbarians, where cavalry screens were necessary.

Allies as intelligence sources

The Romans had always used border tribes to create buffer zones to stymie hostile incursions and to get early warnings about possible invasions. But relying on these federate tribes was unreliable, and the Romans needed expert scouting in depth in the frontier regions beyond their border.⁶⁵ This is what was provided by the exploratores. A barrier like a Hadrian’s Wall was simply a “slowing up” device; it was never meant to hermetically seal the Empire behind an impermeable barrier. If the soldiers manning the wall could be forewarned by their reconnaissance forces operating beyond the Limes, then they could concentrate their forces and strike beyond the wall. They might also be able to spring an attack or at least be ready on the outside of the wall when the enemy arrived. As the eyes and ears of Rome on the border, we cannot overestimate the importance of these troops. Intelligence cannot be improvised and the deeper the penetration, the more time is needed to prepare its successful execution.

Notes

1. Gichon warns against this. There is a basic difference between “scouting by mobile reconnaissance forces in depth and by the operation, observation and listening posts [sic]”. M. Gichon, “Military Intelligence in the Roman Army,” in H.E. Herzig and E. Frei-Stolba (eds), Labor Omnibus Unus. Festschrift Walser, Historia Einzelschriften 60 (Stuttgart, 1989). H.O. Fiebiger, “Exploratores,” RE 4 (1909), cols. 122–5.

2. In Livy 30.4.6 and 30.4.12, the words speculatores and exploratores appear within a few lines of each other, referring to the same spies sent into the camp of Syphax. See F.G. Moore’s note on p. 380 of the Loeb edition. Cicero, Verr 2.5, 63; Cicero, de natura Deorum 3.18.46; Cicero, de natura Deorum 2.56. 140; on speculatores see Sallust, Jug. 101, 1 and Sallust, Jug. 106.2.

3. Dion, of Hal. 9.61.4, Fabius using scouts against the Aequi in 463 bc; Volscian scouts in 8.86.2 and 6.15.3; Roman scouts detecting a Volscian approach 8.82.2; Cavalry scouts 8.37.2; Marcius in Fidenae 3.40.4.

4. Gichon, “Military Intelligence in the Roman Army,” p. 157.

5. See Caesar, BG 2.11.2–3 where Caesar, after the battle of the Aisne, received intelligence on the Belgae from his speculatores who were at forward listening posts, protecting the Roman camp from surprise and reporting on enemy activity.

6. Our earliest references are in Caesar. Inscriptional evidence, of course, tends to date from the imperial period; see CIL 2.4122, 4143, 4145 from the Leg VII Gemina, CIL 3.4843, 5223, 4452, 3524, 4317, 4803, 3021, 1914 Legio X Gemina; CIL 5.7164, 2832; CIL 6.2453, 2528, 2607, 2743, 2755, 2779, 2792, 2796, 3358, 3607, 3629, 3891, 32716, 37235, 32661, 36775; CIL 8.2603, 2793, 2890, 2984, 4381 III Augusta; CIL 10.6674; CIL 13.1869, 8299, 6721, 6884, 1732.

7. J. Kromayer and G. Veith, Heerwesen und Kriegsführung der Griechen und Römer (Munich: C.H. Beck, 1928), p. 356; see also Gichon, “Military Intelligence in the Roman Army,” p. 155.

8. Caesar, BH 13.

9. Gichon, “Military Intelligence in the Roman Army,” p. 157.

10. See C.G. Starr, The Influence of Sea Power in the Ancient World (Oxford: Oxford University Press, 1989), p. 75.

11. They are mentioned in inscriptions along with other military specialists. See CIL 3.4425 from Petronnell in Pannonia Superior, where speculatores dedicate an altar to the Emperor Septimius Severus and his sons, along with the cornicularii and the commentarienses. Similarly, CIL 2.4122 from Tarraconensis shows speculatores again joining the cornicularii and the commentarienses of the Legio VII Gemina to honor their common O.S. in the reign of Septimius Severus and his sons.

12. Gichon, “Military Intelligence in the Roman Army,” p. 167 citing for auxiliary regiments the two forts at El Kantara in North Africa. J. Baradez, Fossatum Africae (Paris, 1949), pp. 235–42. CIL 8.2494, 2495. In independent units: A.S. Hunt, “Register of a Cohort in Moesia,” Raccolti di Scritti in honore di G. Lumbroso (Milan: Aegyptus, 1925), pp. 265–75; A.F.P. Wilcken, Journal of Roman Studies 48 (1958), pp. 102ff.

13. For the use of political agents provocateurs, see Sejanus’s attack on Agrippina and Nero using Lucanius Latiaris. He lured Sabinus to his house, and by feigning sympathy for Agrippina induced him to make injudicious remarks about Tiberius. Sabinus did not realize that Sejanus had agents concealed in the attic keeping record of his every word. He was immediately imprisoned and a report was sent to the emperor. See A.A. Barrett, Caligula. The Corruption of Power (New Haven, CT: Yale University Press, 1989), p. 22.

14. Gichon, “Military Intelligence in the Roman Army,” p. 167; cf. A. Neumann, R-E, “speculatores,” cols. 483ff.

15. Tacitus, Annals 1.6.1, 3; 11.37.4; 15.60.3; Histories 1.85; Starr, Civilization and the Caesars, p. 159; Gichon, “Military Intelligence in the Roman Army,” p. 168. J. Nicole and Ch. Morel, Archives militaires du 1^ere siecle (Geneva: H. Kündig, 1900), pp. 26–7 and 31 show a duty roster from the reign of Domitian from the Legio III Cyrenaica and the Legio XXII Deiotariana from Egypt which mentions a soldier on duty who has been identified by Nicole and Morel, and also by A. von Premerstein, “Die Buchführung einer ägyptischen Legionsabteilung,” Klio 3 (1903), p. 41, as being on “secret plainclothes duty.”

16. M. Speidel, “Exploratores. Mobile Units of Roman Germany,” Epigraphische Studies 13 (1983), pp. 67–70 identifies Tamonius Siluverus of the numerus Melenuensium and Sabinus, a soldier of the numerus Diviriensis as exploratores. Gichon, “Military Intelligence in the Roman Army,” p. 168 suggests they were military intelligence men who are depicted on gravestones in civilian garb.

17. See P.A. Holder, The Roman Army in Britain (New York: St. Martin’s Press, 1982), p. 75 who does not, however, cite the inscription in a note. See RIB 19 now in the British Museum, London, mentioning speculatores from the II Augusta seconded to the governor’s palace in London.

18. Mark 6:27. “And immediately the king sent an executioner, and commanded his head to be brought and he went and beheaded him in prison.” (King James version.) The Greek text uses the Greek word spekoulator, which suggests that although the author was describing Herod’s imperial guard, he was also familiar with the analogous Roman institution and its duties.

19. See Macmullen, Soldier and Civilian, pp. 52–3.

20. Suetonius, Augustus 74.

21. Webster, Roman Imperial Army, p. 91.

22. Suetonius, Augustus 49.3.

23. Tacitus, Annals, 6.50.6.

24. Tacitus, Histories 2.73.1.

25. Website: Ibid., 1.25.1; 1.27.2; 1.35.2. Speculatores also killed Piso 1.43.2.

26. Suetonius, Claudius 35.

27. Josephus, BJ 3.6.2; 5.2.1.

28. A. von Domaszewski, Die Rangordnung des römischen Heeres (Bonn: A. Marcus and E. Weber, 1908), p. 32.

29. J. Baradez, Fossatum Africae (Paris, 1949), pp. 235–42; CIL 8.2494, 2495. Gichon, “Military Intelligence in the Roman Empire,” p. 167.

30. See CIL 8.2494, 2495 for the burgus speculatorum Antonianorum and the burgus Commodianus speculators. On such units elsewhere, see A.S. Hunt, “Register of a Cohort in Moesia,” Raccolti di Scritti in honore di G. Lumbroso (Milan: Aegyptus, 1925), pp. 265–75; A.F.P. Wilcken, Journal of Roman Studies 48 (1958), pp. 102ff.

31. Galba is described as setting off to meet Vitellius’s army attended by praetorians and a “select body of speculatores” (speculatorum lecta corpora). Tacitus 2.11; cf. Suetonius, Galba 18.

32. ILS 2014, 1993 (Vespasian). The central corps called “speculatores of Caesar” belong to the Praetorian Guard, and being mounted were, in effect, a special reinforcement of its cavalry squadrons. Tacitus, Hist. 2.33 describes the escort of Otho as comprising speculatores, praetorians and praetorian cavalry, distinguishing between the two groups. Cf. L. Lammert, “Speculatores,” R-E, vol. 3, A (1929), col. 1585.

33. D. Breeze, “The Organization of the Legion,” Journal of Roman Studies 95 (1969), pp. 51–2 has shown that a speculator legionis appears on the rolls of the sixth cohort, which proves that men chosen as speculatores continued to be connected on a very basic level to their former units.

34. Suetonius, Claudius 25.1. Grant, Army of the Caesars, p. 231. The most thorough treatment is now M.P. Speidel, Riding for Caesar. The Roman Emperors’ Horse Guards (Cambridge, MA: Harvard University Press, 1994).

35. M. Durry, Les Cohorts prétoriennes (Paris, 1938), pp. 28 and 109, n. 1; R.I. Frank, Scholae Palatinae (Rome: American Academy, 1969), p. 29. A. Neumann, R-E, s.v. “frumentarii.”

36. J. Baradez, Fossatum Africae (Paris, 1949), pp. 235–42. CIL 8.2494, 2495.

37. Gichon, “Military Intelligence in the Roman Army,” p. 161.

38. See Speidel, “Exploratores,” pp. 63–78.

39. Arrian, Extasis 1.

40. Website: Ibid., 11.

41. Pseudo-Hyginus, De Munitionibus Castrorum 24.30.

42. See the comments of Gichon, “Military Intelligence in the Roman Army,” p. 159.

43. Arrian, Extasis 4; Gichon, “Military Intelligence in the Roman Army,” p. 162; M. Gichon, “Cestius Gallus’ Campaign in Judaea,” PEQ (1981), pp. 40–62.

44. Gichon, “Military Intelligence in the Roman Army,” p. 160 suggests the legionary exploratores were organized as a turma under the command of a praepositus or a praefectus. See CIL 9.3104 for a praepositus as commander. See CIL 3.3254, CIL 8.9906, and CIL 13.6814 for a praefectus as commander. These were commanders of independent units.

45. Vegetius 3.6: Fidelissimos argutissimosque cum equis probatissimus. Gichon, “Military Intelligence in the Roman Army,” p. 160.

46. Gichon, “Military Intelligence in the Roman Army,” p. 160; M. Speidel, “The Captor of Decebalus,” Journal of Roman Studies 60 (1970), pp. 142–53. For a comparison of his tombstone to the representation on Trajan’s column, see L. Rossi, Trajan’s Column and the Dacian Wars (London: Thames & Hudson, 1971), pp. 229–30. As an alternative explanation of Ti. Claudius Maximus’s career, see N.B. Rankov, “Singulares Legati Legionis: A Problem in the Interpretation of the Ti. Claudius Maximus Inscription from Philippi,” ZPE 80 (1990), pp. 165–75.

47. Pap. Dur 100, 101. Cf. Pap. Brit. Mus. no. 2851, ed. R.O. Fink, Journal of Roman Studies 48 (1958), p. 102. For an explorator serving in an ala of native cavalry, see CIL 8.21516. Cf. E. Stein, Die Kaiserlischen Beamten und Truppenkörper im Römischen Deutschland unter dem Prinzipat (Vienna: W. Seidel, 1932), p. 211.

48. CIL 9.3104; 8.9906; 13.12460 shows a centurio appointed praepositus exploratorum.

49. Gichon, “Military Intelligence in the Roman Army,” p. 163.

50. Website: Ibid., p. 159; Some scholars give more “coherence” to such systems than others. See for example, M. Gichon, “Towers on the Limes Palestinae,” in Actes du Ix^e Congrès Internationale d’Etudes sue les Frontières Romaine (Cologne/Bucharest, 1974), pp. 513, 525.

51. Speidel, “Exploratores”, p. 63–78.

52. On the ranking of these units see ibid.

53. Website: Ibid.

54. Gichon, “Military Intelligence in the Roman Army,” p. 165; Notitia Dignitatum 34.29.

55. According to Speidel, “Exploratores”, large mobile and elite units differed markedly from the smaller, lower-ranking explorationes or exploratores units that garrisoned the forts along the Upper German Limes. See also M. Speidel, “The Rise of Ethnic Units in the Roman Imperial Army,” ANRW 2, 3 (1975), pp. 202–31. On Upper German exploratores units, see E. Stein, Die kaiserlichen Beamten und Truppenkörper im römischen Deutschland unter dem Prinzipat (1932) 260ff. Gichon, “Military Intelligence in the Roman Army”, p. 166 agrees with Speidel in the elite nature of the units, but adds: “there is however no saying whether they operated swifter, more flexibly or more in hostile depth than other units.”

56. Speidel, “Exploratores”, pp. 63–78. For intelligence gathering by exploratores see Vegetius 3.6; Tacitus, Hist. 2.34; Arrian, Extaxis 11; Tacitus, Histories 2.24. See also R. Rebuffat, “Au-delà des camps romains d’Afrique mineure; renseignement, controle, pénétration,” ANRW, vol. 2, 10.2 (1982), pp. 474–513.

57. Gichon, “Military Intelligence in the Roman Army,” p. 166 has argued that Speidel, while identifying these outfits as elite, “never produced any evidence for the tactical employment of these troops.” Gichon doubts whether they acted any swifter, more flexibly or further into hostile territory than other units.

58. The ala exploratorum Pomariensium at Tlecmen; see N. Bennseddik, Les troupes auxiliaries de l’armée romaine en Mauretanie Césarienne sous le haut-empire (Algers: SNED, 1979).

59. For the cohors IX Batavorum equitata exploratorum at Passau, see Speidel, “Exploratores”, p. 74, n. 50.

60. Website: Ibid. In Britain, some of the wall outposts had numeri Exploratorum cobrigaded with primary garrisons of military cohortes equitata.

61. They can also be found at Roomberg, Divitia (Deutz) on the eastern side of the Rhine, Hesselbach, Feldberg. Miltenberg, Passau (Castra Batava). Gichon, “Military Intelligence in the Roman Army,” p. 165.

62. Contra J.W. Eadie, “Barbarian Invasions and Frontier Politics in the Reign of Gallienus,” in Roman Frontier Studies 1979 (eds W.S. Hansen and L.J.F. Keppie, 1980), vol. 3, pp. 1045–50.

63. Stein, Kaiserlichen Beamten und Trüppenkorper, p. 260. See Gichon, “Military Intelligence in the Roman Army,” p. 165, n. 47.

64. Zosimus 3.14.1; 15.2; 15.4; 24.1. See also Gichon, “Military Intelligence in the Roman Army,” p. 162.

65. Their privileged status implied strict discipline, as can be seen from the severe punishments that were meted out for dereliction of duty, according to a law in the Digest XLIX, 16, 3 and 5.