Civil wars of the Tetrarchy: An outnumbered army led by Roman emperor Licinius defeated his rival Maximinus II's forces at the Battle of Tzirallum. Licinius: Valerius Licinianus Licinius was Roman emperor from 308 to 324. For most of his reign, he was the colleague and rival of Constantine I, with whom he co-authored the Edict of Milan that granted official toleration to Christians in the Roman Empire. He was finally defeated at the Battle of Chrysopolis, and was later executed on the orders of Constantine. April 30, 313. Wiki link