Library Eusebius of Caesarea Life of Constantine
Book 1, Chapter 46: Victories over the Barbarians.
Thus the emperor in all his actions honored God, the Controller of all things, and exercised an unwearied oversight over His churches. And God requited him, by subduing all barbarous nations under his feet, so that he was able everywhere to raise trophies over his enemies: and He proclaimed him as conqueror to all mankind, and made him a terror to his adversaries: not indeed that this was his natural character, since he was rather the meekest, and gentlest, and most benevolent of men.
English translation by Ernest Cushing Richardson, in Nicene and Post-Nicene Fathers, Series II, Vol. I (eds. Philip Schaff and Henry Wace; Buffalo: Christian Literature Publishing Co., 1890). Public domain. Digital text via New Advent Church Fathers.