Frumentarii

It had been a long-standing policy of the Roman legions and armies of occupation to utilize informers and spies, but never in an organized fashion.

[4][5][6] During their early history, they were tasked with supplying grain to the military, delivering messages between the provinces and the empire,[7][8] and collecting tax money.

But even an emperor could not easily create a new bureau with the express purpose of spying on the citizens of Rome's far-flung domains.

[18] He used the frumentarii as a spying agency because their duties brought them into contact with enough locals and natives, allowing them to acquire considerable intelligence about any given territory.

[39] The following story has been used as evidence of the role of the frumentarii:[40] [Hadrian's] vigilance was not confined to his own household but extended to those of his friends, and by means of his private agents (frumentarios) he even pried into all their secrets, and so skilfully that they were never aware that the Emperor was acquainted with their private lives until he revealed it himself.

The wife of a certain man wrote to her husband, complaining that he was so preoccupied by pleasures and baths that he would not return home to her, and Hadrian found this out through his private agents.

".The Frumentarii are rarely depicted in fiction, yet, quite often, most likely for scenaristic reasons, their role is regularly mixed with the speculatores.

Such view is actually present in the work of a few authors, such as: Juan Manuel Sánchez Valderrama,[41] G. K. Grasse[42] orAlex Speri.