Life of Constantine

Thus the emperor and his army had long been accustomed to act, whenever there was a prospect of an engagement; for his God was ever present to his thoughts, and he desired to do everything according to his will, and conscientiously to avoid any wanton sacrifice of human life. He was anxious thus for the preservation not only of his own subjects, but even of his enemies. Accordingly he directed his victorious troops to spare the lives of their prisoners, admonishing them, as human beings, not to forget the claims of their common nature. And whenever he saw the passions of his soldiery excited beyond control, he repressed their fury by a largess of money, rewarding every man who saved the life of an enemy with a certain weight of gold. And the emperor's own sagacity led him to discover this inducement to spare human life, so that great numbers even of the barbarians were thus saved, and owed their lives to the emperor's gold.