M. Aurelius Valerius Maximianus was from Dalmatia (now Yugoslavia), a fellow countryman of the emperor Diocletian. In 286 A.S. Diocletian elevated him to the rank of Augustus, placing him in charge of the western half of the extensive Roman Empire. Seven years later, 293 A.D., each Augustus was assigned a Caesar to help him govern, thus forming the system known as the tetrachy. In 305 A.D. Diocletian and Maximianus both abdicated their power as Augusti. A period of political complications followed, resulting in Maximianus' son Maxentius coming to power and inviting his father to re-assume his role. Maximianus, who had been reluctant to abdicate in 305, readily agreed to become emperor again in late 306. Maximianus strengthened. His power by forming an alliance with the Augustus Constantine the Great and arranging for the marriage of Constantine and Maximianus' daughter. Maximianus later quarreled with his son Maxentius and fled Rome for the protection offered by Constantine. A conference was held between all claimants for the tetrachic thrones, resulting in the forced abdication of Maximianus. In 310, Maximianus revolted against Constantine and was proclaimed emperor for the third time. Constantine then besieged Maximianus in Massilia (Marseilles), and soon after the fall of the city, the emperor died.