The foreign intelligence service of Late Rome and Early Byzantium, which was regarded by contemporaries almost unanimously as exemplary, no doubt deserves our attention, although this topic, for unknown reasons, has been extremely poorly studied by Russian historical science.
To begin with, let's say that late Roman foreign intelligence was divided, in modern terms, into three levels: strategic, operational and tactical.
The main goal strategic intelligence In the late Roman and early Byzantine empires, there was a collection of as detailed information as possible about the enemy's armed forces, their locations, as well as data on its economic and mobilization potential long before the start of military confrontation. This information was collected from various sources, the main of which were four:
1. Special agents who worked deep in enemy territory (often recruited from migrants who, for one reason or another, migrated to the borders of the empire).
2. Agents who carried out reconnaissance in the adjacent border areas.
3. Persons who were in the diplomatic service.
4. Agents of influence in the enemy country.
Special agents of "deep penetration" were probably one of the most important sources of intelligence information (in particular, information has been preserved that, through the state intelligence service, the late Roman emperors received information from agents working in the territory of modern Iran about the events that took place in Central Asia on the eastern borders of the New Persian kingdom) …
And it was their work that was associated with the greatest risk, since they closely communicated with the local population, being in the depths of the enemy state and having no protection.
The outstanding late Roman historian Ammianus Marcellinus, himself a former officer at the headquarters of the emperor, provides some information about the actions of these agents. For example, he says that experienced agents called "speculatorii" ("speculators", yes, the well-known modern word "speculators", denoting clever dealers and schemers, goes back to this term) must master the art of tracking and be able to beyond recognition change your appearance.
The anonymous author of the surviving late Roman treatise, De re Strategica, also provides some interesting details. Thus, he notes that the imperial agents at that time "worked in pairs" and always had a number of agreed places to meet with each other to exchange information. It is emphasized that one of the main sources of information is the market squares of large cities, where merchants and other people from various countries arrive, and where you can hear the latest and most important news, and at the same time it is easy to get lost in the motley crowd.
It is here, in the square or market, according to the unknown ancient author, that the agent collecting information can meet with his informants. And then, according to the form of making a purchase, transfer them to your colleague for subsequent secret transfer to the empire.
It is quite possible that, acting through such "agents of deep penetration", the prefect of the imperial praetorium Muzonian, who oversaw the intelligence service of the East together with the Dux of Mesopotamia Cassian, received information from the distant borders of the New Persian state.
According to Ammianus Marcellinus, "dexterous and skillful in deception" agents called "emissarii" ("emissaries") or "speculatorii" reported to the leadership of the empire at a critical moment information about the forced start of a difficult war of the Persian king on the border lines, which required the involvement of forces from the western direction and made the Persian diplomats more accommodating.
Agents who carried out reconnaissance in the territories immediately adjacent to the borders of the empirewere less experienced scouts; they could be hired both from the natives of those areas, and simply from the citizens of the empire. This category of persons was created as a special intelligence structure during the reign of Emperor Constant (337-350 AD) and was called "arcani" ("arcana"). It is difficult to say what is the connection of this 1500-year-old Latin term with the possibly somewhat later Turkic name for the rope lasso used by nomads to seize prey, but perhaps there is.
These special agents could be as quiet and inconspicuous people as the "emissaries" who worked in the guise of merchants, and could perform, if necessary, power functions (for example, a group of "lasso" could be sent with the task to secretly kidnap or kill a particularly implacable leader of the border " barbarian "tribe, plotting a raid on the lands of the empire).
However, the main function of the "lasso" was to conduct comprehensive reconnaissance in the borderlands, monitor the state of mind in the "barbarian tribes", as well as, if necessary, assist in the transfer of information from agents of the aforementioned categories 1 and 3 to the late Roman state.
True, if agents of deep penetration were, let's say, a piece of goods, then "lasso" were more numerous, and therefore a relatively less reliable category. So, among them there were sometimes cases of betrayal of the state interests of the empire.
For example, the fact revealed by the "security service" of the Emperor Theodosius the Elder has survived: in 360, representatives of the "arcane" service on the coast of Roman Britain and on the "Saxon coast" came into contact with the leaders of the barbarian tribes who hunted sea piracy, and for money they "poured" to them information about the weakening of the forces of the Roman patrol service, about places of accumulation of values, etc.
The third category of strategic intelligence agents in Late Rome and Early Byzantium was persons officially acting as diplomats. As elsewhere, the ambassadors of the empire were simultaneously spies. Protected by diplomatic immunity, and who reported critical news to the emperor's headquarters. For example, the Roman authorities received a message about the preparation of the upcoming Persian invasion of the eastern provinces of the empire from the notary Procopius, who went with the embassy to Persia to negotiate peace.
There is information that before getting to the headquarters of the emperor, a secret agent delivered information to the fortress Amida, which covered the borders of the empire from the Mesopotamian direction, and the master of the cavalry, Urzitsin, who was there, had already sent this message with a detachment of horsemen to the headquarters. At the same time, the message itself was a small piece of parchment, covered in secret writing and hidden deep in the sheath of the sword.
A special category of agents of strategic intelligence in the era of Late Rome and Early Byzantium was agents of influence in the enemy country. Identifying such a person and establishing confidential contact with him was considered an important task of diplomats and secret agents of foreign strategic intelligence.
In the power structure of the same New Persian kingdom, there were people who could occupy significant posts, but for one reason or another secretly sympathized with the Roman Empire. Most often, these were representatives of confessional (Christians in the Sassanid state) or ethnic minorities (Armenians in the administrative apparatus of the same New Persian kingdom), who made contact with the enemy because of their religious beliefs, or people who did it because of the injustice of the rulers.
So, there is evidence that such an agent of influence in the New Persian kingdom was the satrap of Corduena Jovian, a secret Christian who spent his childhood as a noble hostage in Roman Syria. And it was precisely such agents of influence in the power structure that became a source of valuable information or provided assistance to imperial agents.
Operational Intelligence of Late Rome and Early Byzantium usually began to function at the beginning of an armed confrontation and partly merged in its functionality with the strategic, and partly with the tactical. In a sense, the service of the "arcana", which we talked about above, and which were supposed to conduct observation on the lands of the "barbarians" bordering the empire, can also be attributed to it.
However, first of all, it included skillful and observant officers, whom the commander of the army, or, less often, the governor of the province, sent in order to "analyze the situation on the spot" and to carry out direct observation of the enemy, who is still operating at a sufficient distance.
In particular, these functions were performed in his youth by the aforementioned late Roman historian Ammianus Marcellinus, who, while serving on the Persian border, was sent to Mesopotamia, to the territory of modern Iraq, in order to monitor the gatherings and movements of the armies of the Persians.
The functions of active or mobile operational-tactical reconnaissance in the late Roman period were also performed by "explorats", "scouts" ("exploratores", literally: "researchers"). Originating as tactical scouts in the Roman army as early as the era of Octavian Augustus, these soldiers in the early 2nd century AD. were consolidated into separate units (numbering approximately from 50 to 100 people), usually operating far ahead of the main forces. Their main goal was to clarify the most convenient and safest route for the army, in parallel with identifying the location of the enemy's forces and monitoring them in order to prevent unexpected attacks.
In the late Roman period, due to the increase in the strength and mobility of the enemies of the empire, the scout units only increased and new categories were formed. In particular, on the model of the Sarmatian and Arab federates and on their basis, equestrian units of "procursors" ("procursatores", literally "walking in front") were created in late Roman times.
In some ways, the functions of these formations were similar to the role of the later "ertouls" and "flying regiments" - they were relatively large and highly mobile formations that were supposed to conduct deep operational-tactical reconnaissance, as well as raid enemy communications and carts. Their number can be judged by the following fact: in the army of Emperor Julian, which acted against the Alemanni Germans in the area of modern Strasbourg, the number of which is estimated at about 13-15 thousand soldiers, there were up to 1500 horsemen.
Tactical intelligence level, as you know, involves the direct collection of information about the enemy already in the course of a military conflict in direct contact with enemy formations. In the era of Late Rome and Early Byzantium, tactical intelligence, just like in our time, can be divided into passive (static) and active (mobile).
Static intelligence information was collected by collecting data from fortified borders ("Limes"), and from enemy defectors. From outposts on both fortified and unfortified borders, information about the enemy was transmitted either by means of smoke / fire signals, or by special couriers.
According to the data of the late Roman military theorist Flavius Vegetius Renatus, at that time there was already a system of daytime visual transmission between posts of the simplest codes containing basic data on the strength of the enemy and the direction of the invasion.
Mobile military intelligence, according to Ammianus Marcellinus, was always carried out by the imperial troops if the enemy was already in relative proximity. In this case, small mounted patrols were sent in all directions from the army in order to establish the exact location of the enemy's forces (one could say that the star-shaped patrol system is in some sense a 1,500-year-old analogue of modern radar pulses).
Basically, for this, light-window units were used, called "excursatores" ("excursionists" - "observers", "examining"), but often tactical scouts were also assembled from the composition of other cavalry formations.
It seems to be an objective opinion that, in fact, the "excursionists" were an analogue of the earlier ancient Greek and Macedonian "prodroms" ("runners"), which performed the functions of mobile close reconnaissance.
Sources note that late Roman and early Byzantine scouts not only set out from the camp at night, but often operated in the darkness of the night with the aim of better stealth and with the possibility of obtaining better conditions for detecting enemy ambushes.
A very important function of tactical scouts was considered then, as, however, it is considered now, the capture of prisoners (preferably senior officers) in order to obtain from them valuable information about the forces and plans of the enemy.
Summing up the outcome, we can say the following: in comparison with the era of the republican principate, foreign intelligence in the period of Late Rome and Early Byzantium not only did not worsen the performance of its functions, but, on the contrary, actively developed, improving both organizationally and qualitatively.
And it was precisely the seriously improved structure of foreign military intelligence that allowed the leading world empire in that era, already very distant from us, not only to withstand the sharply increased external military pressure and permanent financial crises, but also to move to the next stage of civilizational development.
