Origins of thefrumentarii The existence of the Augustan postal, road, and communications infrastructure, combined with the centralization and absolutism developing in the new imperial system, created an environment perfect for spawning an internal security service. It is possible to identify from the first century AD onwards a body based in the capital that acted as an internal security agency throughout the Empire. This unit was called the frumentarii, and it was housed in the Castra Peregrina or "Foreigners' Camp" on the Caelian Hill in Rome. These men were legionary soldiers who acted as couriers between the provincial capitals and Rome, but who could also be assigned duties that included tax collecting, espionage, and political assassination.