Constantine rose to power during a bloody struggle in Roman Britain and was acclaimed emperor by the local legions in 407. He promptly moved to Gaul, taking all of the mobile troops from Britain, to confront the various Germanic invaders who had crossed the Rhine the previous winter. Constantine gained the upper hand after several battles with the forces of the Western Roman Emperor Honorius. As a result, Honorius recognised Constantine as co-emperor in 409. The activities of the invading tribes, raids by Saxons on the near-defenseless Britain and desertions by some of his top commanders led to a collapse of support. After further military setbacks he abdicated in 411. He was captured and executed shortly afterwards.