There appears to have been a serious setback at the hands of the tribes of the Picts of Alba around 105 CE: several Roman forts are destroyed by fire, with human remains and damaged armor at Trimontium (at modern Newstead, in southeast Scotland) indicating hostilities at least at this site.

There is also circumstantial evidence that auxiliary reinforcements were sent from Germany, and an unnamed British war of the period is mentioned on the gravestone of a tribune of Cyrene.

However, Trajan's Dacian Wars may have led to troop reductions in the area or even total withdrawal followed by slighting of the forts by the Picts rather than an unrecorded military defeat.

The Romans are also in the habit of destroying their own forts during an orderly withdrawal, in order to deny resources to an enemy.

In either case, …