At Mediolanum (Milan) on March 1, 293, Constantius was formally appointed as Maximian's Caesar. He adopted the name "Flavius Valerius Constantius", and, being equated with Maximian, also took on "Herculius". His given command consisted of Gaul, Britannia and possibly Hispania. Diocletian, the eastern Augustus, in order to keep the balance of power in the "imperium", elevated Galerius as his Caesar, possibly on May 21, 293 at Philippopolis (Plovdiv). Constantius was the more senior of the two Caesars, and on official documents he always took precedence, being mentioned before Galerius. Constantius' capital was to be located at Augusta Treverorum (Trier).