War with LiciniusBosporus, Turkey
In the following years, Constantine gradually consolidated his military superiority over his rivals in the crumbling Tetrarchy. In 313, he met Licinius in Milan to secure their alliance by the marriage of Licinius and Constantine's half-sister Constantia. During this meeting, the emperors agreed on the so-called Edict of Milan, officially granting full tolerance to Christianity and all religions in the Empire. The conference was cut short, however, when news reached Licinius that his rival Maximinus had crossed the Bosporus and invaded European territory. Licinius departed and eventually defeated Maximinus, gaining control over the entire eastern half of the Roman Empire. Relations between the two remaining emperors deteriorated, as Constantine suffered an assassination attempt at the hands of a character that Licinius wanted elevated to the rank of Caesar; Licinius, for his part, had Constantine's statues in Emona destroyed.