Elliott, Simon Roman Special Forces and Special Ops. Speculatores, Exploratores, Protectores and Areani in the Service of Rome

Much has been written about the Roman army and the mighty legions that conquered their empire and then defended it for centuries against all comers. But little has been written about the men and units employed when something more subtle than the march of legions into pitched battle was required. This is the only book available dedicated to Roman special ops and the role of the Speculatores, Exploratores, Protectores and Areani.
Simon Elliott reveals the kinds of special operations conducted by the Romans: tactical scouting ahead of the legions, covert strategic reconnaissance in neighbouring states, espionage, assassination or abduction of dissidents and enemies, counter-insurgency, and close protection of Roman officials and commanders.

While such missions were frequently executed by ad-hoc units or individuals detailed for that specific mission, the author goes on to reveal the evidence for the aforementioned specialist units. He concludes with an analysis of the extent to which these various forces corresponded to a modern conception of Special Forces. These men were the eyes and ears of the Empire, the deadly tip of the Roman sword.