312

By place

Roman Empire

• Constantine the Great crosses the Cottian Alps with an army and auxiliaries. He defeats Maxentius in three battles at Turin, Brescia and Verona. Maxentius's most senior commander Ruricius Pompeianus is killed during the fighting.
• October 28 - Battle of the Milvian Bridge: Constantine I defeats usurper Maxentius at the Milvian Bridge and becomes the only Roman emperor in the West. During the battle, he reportedly has a vision of a cross with the phrase "in hoc signo vinces".
• October 29 - Constantine I enters Rome; he stages a grand adventus in the city, and is met with popular jubilation. Maxentius' body is fished out of the Tiber and decapitated.
• Constantine I forges an alliance with co-emperor Licinius, and offers him his half-sister, Constantia, in marriage. The Praetorian Guard and Imperial Horse Guard are disbanded.
• Construction begins on the Arch of Constantine in Rome. On a sculptural relief Constantine I addresses the people in the Roman Forum.

  By topic

Religion

• Constantine I adopts the words "in hoc signo vinces" as a motto and has the letters X and P emblazoned on the shields of his soldiers.
• The Council of Carthage supports Donatism, which espouses a rigorous application and interpretation of the sacraments. These doctrines will be condemned by the Council of Arles.
• Constantine I promotes a policy of state sponsorship of Christianity, perhaps even becoming a Christian himself.