Since the hurried journey of Hogarth and Yorke in 1894, the Euphrates limes has remained virtually unexplored, and uncertainty has continued to surround its geography and organization.
The basic structure, established under Vespasian and consolidated by Hadrian, and many of the details of its course, can now be located on the ground. Three legionary fortresses—at Satala (Plate IV, 1), Melitene and Samosata, with legionary vexillations (replaced under Diocletian by a new legion) at a fourth at Trapezus—blocked the major strategic routes from the east, and are already well known. They were linked by an eight metre military road, whose remains I have managed to trace on foot, almost without a break, for a hundred miles north of Melitene, along the right bank of the Euphrates: barely a fifth of the total distance from the Black Sea to the southern foothills of the Kurdish Taurus. A series of auxiliary forts seems to have stood on, or at points east of, the road at intervals of a day's march. Most of the sites hitherto proposed—by armchair inspection of inaccurate maps—should be dismissed, but genuine sites have proved elusive. Only at Dascusa has excavation been possible, to reveal fourth-century work, rather than the original fort. But an important inscription in re-use attests military activity under Titus or Domitian: along with the Pompeius Collega milestone, it provides confirmation of scattered literary and numismatic evidence for Vespasian's hand in the building of the frontier.