Licinius was born in Upper Moesia in about AD 250 as the son of a peasant. He rose through the ranks of the military and became the friend of Galerius, being rewarded with a military command on the Danube.
At the conference of Carnuntum in AD 308 Licinius was, on the behest of his old friend Galerius, suddenly raised to the rank of Augustus, adopted by Diocletian and, granted the territories of Pannonia, Italy, Africa and Spain, the latter three only in theory, as ther were still occupied by the Usurper Maxentius.
Knowing that only his friendship with Galerius had made him Emperor, Licinius, hoping to stave off confrontation with other strong, bonafide claims to the throne, allied himself with the Claimant Constantine by becoming engaged to, and subsequently marrying Constantine’s sister Constantia.
Licinius’ alliance with Constantine was fairly successful, although many battles and deaths would result before they were secure. To all intents, the two emperors would for many years peacefully co-exist without one challenging the authority of the other.