Mardis (War of the Two Empires).
Fought 315, shortly after the battle of Cibalis, between Constantine, Emperor of the West, and Licinius, Emperor of the East. Constantine moved a body of 5,000 men round his opponent's flank, and attacked him simultaneously in front and rear. The Illyrian veterans formed a double front, and held their ground, though with heavy loss, till nightfall, when Licinius, having lost thousands of his best troops, drew off his army towards the mountains of Macedonia. The consequence of this defeat was the acquisition by Constantine of Pannonia, Dalmatia, Dacia, Macedonia and Greece.