Zosimus, New History 2.26
Zosimus (Greek Ζώσιμος): Early Byzantine, pagan author of a history of the Roman Empire, published in the first quarter of the sixth century CE.
The translation of Zosimus' New History offered here was printed in 1814 by W. Green and T. Chaplin in London, and was probably prepared by J. Davis of the Military Chronicle and Military Classics Office. The translator is anonymous. The text was found at Tertullian.org. The notes were added by Jona Lendering.
[2.26.1] While Licinius was thus occupied, Constantine, who had a great number of transports as well as warlike vessels, and was desirous to make use of them in crossing over and possessing himself of the opposite shore, fearing that the Bithynian coast might be inaccessible to ships of burden, immediately constructed some small vessels, with which he sailed to the Sacred Promontory, which lies at the entrance of the Pontus, two hundred stadia from Chalcedon. He there landed his army, which, having done, he drew them up upon some adjacent hills.
[2.26.2] Licinius, though he then saw that Bithynia was already in the hands of his enemy, was rendered so desperate by danger, that he sent for Martinianus from Lampsacus, and in order to encourage his men to fight, told them that he himself would lead them. Having said what he thought necessary to encourage them, he drew them up in order of battle, and marching out of the city, met the enemy, who were prepared for him.
[2.26.3] A sharp engagement taking place between Chalcedon and the Sacred Promontory, Constantine had the superiority, for he fell on the enemy with such resolution that of a hundred and thirty thousand men, scarcely thirty thousand escaped. When the Byzantines heard of this, they immediately threw open their gates to Constantine, as did the Chalcedonians also. Licinius after this defeat went to Nicomedia with what horse were left him, and a few thousands of foot.