 The fight against Allectus may have led to the frontier being denuded of troops in the late 3rd century, with consequent attacks from the north.There is evidence of fire-damage at Ravenglass and other damage elsewhere in the north.The emperor Constantius I came to Britain twice to put down trouble (in 296, defeating Allectus, and in 305 fighting the Picts), and there is evidence of re-building taking place.