As Honorius could no more guarantee the defense of Britain, he suggested the provincials to provide for their own protection in 410. The influx of Roman coins stopped, indicating that Britain ceased to be an integral part of the Roman world. The Vandals and their allies took control of most Roman provinces in Iberia, and Alaric's successor, Athaulf led the Visigoths to Gaul from Italy. Maximus attacked Constantine III in Gaul, but his troops deserted him on the unexpected arrival of Honorius' army under the command of the general Constantius. Maximus fled, and Constantine III was executed, but Western Roman unity was not restored. With the support of the Burgundians, Alans and Visigoths, a Gallic aristocrat Jovinus was declared emperor on the Rhine. His alliance with the Visigoths proved transitory because Honorius convinced Athaulf to desert Jovinus promising food supply to his people. Although Athaulf murdered Jovian, the Romans failed to deliver the promised grain. Athaulf married Honorius' half-sister Galla Placidia who had been captured during the sack of Rome, but fell victim to a Visigothic conspiracy in 415. Constantius restored Roman rule in southern and central Iberia and ceded Aquitania Secunda to the Visigoths in return for their assistance against the Vandals, Alans and Suebi.