Constantius was a son of Constantine the Great, who elevated him to the imperial rank of "caesar" on 8 November 324 and after whose death Constantius became "augustus" together with his brothers, Constantine II and Constans on 9 September 337. He promptly oversaw the massacre of his father-in-law, an uncle and several cousins, consolidating his hold on power. The brothers divided the empire among themselves, with Constantius receiving Greece, Thrace, the Asian provinces and Egypt in the east. For the following decade a costly and inconclusive war against Persia took most of Constantius's time and attention. In the meantime, his brothers Constantine and Constans warred over the western provinces of the empire, leaving the former dead in 340 and the latter as sole ruler of the west. The two remaining brothers maintained an uneasy peace with each other until, in 350, Constans was overthrown and assassinated by the usurper Magnentius.