Diatribe de Prodigiosis Crucibus

In truth, events have taught that the Church has always shone the more gloriously and flourished the more abundantly with Divine virtue, the more it was thought to have been extinguished by the arms of the impious.

From the appearing Crosses, a favorable sign.

In the year 395, when the Emperor Arcadius had declared a difficult war in favor of the Armenians against the Persians, and as the soldiers were already gathering for battle, burning with an incredible fervor of spirit, behold: suddenly, aerial Crosses appeared upon their garments—a brilliant indication of the victory that was to be obtained against the enemy. From this, the victor transmitted a gold coin, imprinted with this same sign of the Cross, to the memory of posterity. So says Prosper.

In the year 419, during which many cities and villages in Palestine were collapsed by an earthquake, Christ our Savior gave Himself to be seen upon the Mount of Olives from a luminous cloud; upon seeing and hearing which, many nations still immersed in the darkness of heathendom embraced the faith of Christ, and—wondrous to relate—upon the garments and tunics of those washed in the sacred font of baptism, the image of the Cross of Christ immediately appeared. Marcellinus describes these things more fully in his Chronicle.

Crosses appear on the garments of the baptized.