on october 28th in 312 a.d., emperors maxentius and constantine and their armies met on the banks of the tiber river near the milvian bridge to fight for control of the empire. though constantine's soldiers were outnumbered four to one, he had a secret weapon. >> before the battle, he had a vision in which he saw a sign of the cross in the sky, and the words written over it that said "by this conquer" he didn't know what this meant, so he called in some dream interpreters, and they told him this meant that it was the cross of christ that would allow him to be victorious. and so he arranged to have the image of the cross painted on