Res Gestae

Also, when Constantine was at Thessalonica, the Goths broke through the neglected frontiers, devasted Thrace and Moesia, and began to drive off booty. Then because of fear of Constantine and his check of their attack they returned their prisoners to him and peace was granted them. But Licinius complained of this action as a breach of faith, on the ground that his function had been usurped by another.

Finally, by using sometimes humble entreaties and sometimes arrogant threats, he aroused the deserved wrath of Constantine, During the interval before the civil war began, but while it was in preparation, Licinius

Now peace was broken by consent of both sides; Constantine sent Crispus Caesar with a large fleet to take possession of Asia, and on the side of Licinius, Amandus opposed him, likewise with naval forces.

Licinius himself had covered the slopes of a high mountain near Hadrianopolis with a huge army. Hither Constantine turned his march with his entire force. While the war went on slowly by land and sea, although Constantine’s army had great difficulty in scaling the heights, at last his good fortune and the discipline of his army prevailed, and he defeated the confused and disorganised army of Licinius;[*](324 A.D.) but Constantine was slightly wounded in the thigh.