He became embroiled in the Civil wars of the Tetrarchy between rival claimants for control of the empire, in which he was defeated by Licinius.
Shortly before the great persecutions of Diocletian and Maximinus II, he withdrew as a hermit to a mountain about six kilometres from Sarsina which is now named after him (Monte San Vicinio, in the present commune of Mercato Saraceno).