Res Gestae

From there, taking with him his wife, his son, and his treasures, he went to Dacia and appointed Valens, who was commander on the frontier, to the rank of Caesar. Then, having through Valens mustered a large force at Hadrianopolis, a city of Thrace, he sent envoys to Constantine, who had established himself at Philippi, to treat for peace. When the envoys were sent back without accomplishing anything, the war was renewed and the two rivals joined battle on the plain of Mardia. After a long and indecisive struggle, the troops of Licinius gave way and night aided them to escape.

Thereupon Licinius and Valens, believing that Constantine (as turned out to be the case), in order to follow up his advantage, would advance farther in the direction of Byzantium, turned aside and made their way towards Beroea.[*](A town of Thrace; cf. Amm. xxvii. 4, 12; xxxi. 9, 1.) As Constantine was eagerly pushing on, he learned that Licinius had remained behind him; and just then, when his men were worn out from fighting and marching, Mestrianus was sent to him as an envoy, to propose

Then Constantine, having returned to Serdica, arranged with Licinius, who was elsewhere, that Crispus and Constantinus, sons of Constantine, and Licinius, son of Licinius, should be made Caesars, and that thus the rule should be carried on in harmony by both emperors. Thus Constantine and Licinius became colleagues in the consulship.[*](In 319.)

In the regions of the Orient, while Licinius and Constantine were consuls, Licinius was stirred by sudden madness and ordered that all the Christians should be driven from the Palace.[*](Orosius uses the same language.) Soon war flamed out again between Licinius himself and Constantine.