It is believed that while on one of his wars of conquest he saw a cross in the sky, as well as the following words: In hoc signo vinces (In this sign you will find victory).
Inasemekana kwamba wakati mmoja, alipokuwa safarini kwenda vitani, aliona msalaba angani uliokuwa na maandishi yafuatayo: In Hoc Signo Vinces (Katika Ishara hii utapata Ushindi).