Death of Maximin, who had attempted a Conspiracy, and of Others whom Constantine detected by Divine Revelation
While he was thus engaged, the second of those who had resigned the throne, being detected in a treasonable conspiracy, suffered a most ignominious death. He was the first whose pictures, statues, and all similar marks of honor and distinction were everywhere destroyed, on the ground of his crimes and impiety. After him others also of the same family were discovered in the act of forming secret plots against the emperor; all their intentions being miraculously revealed by God through visions to His servant.
For he frequently vouchsafed to him manifestations of himself, the Divine presence appearing to him in a most marvelous manner, and according to him manifold intimations of future events. Indeed, it is impossible to express in words the indescribable wonders of Divine grace which God was pleased to vouchsafe to His servant. Surrounded by these, he passed the rest of his life in security, rejoicing in the affection of his subjects, rejoicing too because he saw all beneath his government leading contented lives; but above all delighted at the flourishing condition of the churches of God.
Source: Life of Constantine (New Advent)