
Maxentius destroyed the bridges crossing the Tiber, making it difficult for Constantine to amass a coherent and directed assault. At the site of the Milvian Bridge north of the city, Maxentius had a temporary pontoon bridge built. He crossed it with his army and awaited Constantine.
According to Eusebius and Lactantius, the face off between Constantine and Maxentius marked the beginning of Constantine's conversion to Christianity. Eusebius says that Constantine had a vision, hearing the words “Ἐν Τούτῳ Νίκα,” “in this (image) conquer” and the image of ☧ , a Chi-Rho, the first two letters of the word “Christ” in Greek.
Taken as God’s declaration of victory for the soon-to-be-Emperor. The ☧ was painted on all of Constantine’s soldiers's shields.