Fortress of Spears: Empire III by Anthony Riches
'A master of the genre' The Times
The Romans have vanquished the rebel alliance; Calgus, Lord of the Northern Tribes, is the prisoner of the chieftains he once led. And the Roman leader has an audacious plan to capture Dinpaladyr, the barbarians' fortress of spears.
Marcus Aquila - burning for revenge on an enemy that has killed one of his best friends - rides north with the Petriana cavalry. He believes his disguise as Centurion Corvus of the 2nd Tungrians is still holding.
But he is just a few days ahead of two of the emperor's agents, sent from Rome to kill him. Pitiless assassins who know his real name, and too much about his friends.