That he reigned above Thirty Years, and lived above Sixty
With respect to the duration of his reign, God honored him with three complete periods of ten years, and something more, extending the whole term of his mortal life to twice this number of years. And being pleased to make him a representative of his own sovereign power, he displayed him as the conqueror of the whole race of tyrants, and the destroyer of those God-defying giants of the earth who madly raised their impious arms against him, the supreme King of all. They appeared, so to speak, for an instant, and then disappeared: while the one and only true God, when he had enabled his servant, clad in heavenly panoply, to stand singly against many foes, and by his means had relieved mankind from the multitude of the ungodly, constituted him a teacher of his worship to all nations, to testify with a loud voice in the hearing of all that he acknowledged the true God, and turned with abhorrence from the error of them that are no gods.
Source: Life of Constantine (New Advent)