Iam mota inter eos fuerant arma civilia. et quamvis se Maxentius Romae contineret, quod responsum acceperat periturum esse, si extra portas urbis exisset, tamen bellum per idoneos duces gerebatur. plus virium Maxentio erat, quod et patris sui exercitum receperat a Severo et suum proprium de Mauris atque Gaetulis nuper extraxerat. dimicatum, et Maxentiani milites praevalebant, donec postea confirmato animo Constantinus et ad utrumque paratus copias omnes ad urbem propius admovit et a regione pontis Mulvii consedit. imminebat dies quo Maxentius imperium ceperat, qui est a.d. sextum Kalendas Novembres, et quinquennalia terminabantur. commonitus est in quiete Constantinus, ut caeleste signum dei notaret in scutis atque ita proelium committeret. facit ut iussus est et transversa X littera, summo capite circumflexo, Christum in scutis notat. quo signo armatus exercitus capit ferrum. procedit hostis obviam sine imperatore pontemque transgreditur, acies pari fronte concurrunt, summa vi utrimque pugnatur: neque his fuga nota neque illis.
(Lactantius, Mort. Pers. 44.1-6)
And now a civil war broke out between Constantine and Maxentius. Although Maxentius kept himself within Rome, because the soothsayers had foretold that if he went out of it he should perish, yet he conducted the military operations by able generals. In forces he exceeded his adversary; for he had not only his father’s army, which deserted from Severus, but also his own, which he had lately drawn together out of Mauritania and Italy. They fought, and the troops of Maxentius prevailed. At length Constantine, with steady courage and a mind prepared for every event, led his whole forces to the neighbourhood of Rome, and encamped them opposite to the Milvian bridge. The anniversary of the reign of Maxentius approached, that is, the sixth of the kalends of November [i.e. the 27th of October], and the fifth year of his reign was drawing to an end. Constantine was directed in a dream to cause the heavenly sign to be delineated on the shields of his soldiers, and so to proceed to battle. He did as he had been commanded, and he marked on their shields the letter Χ, with a perpendicular line drawn through it and turned round thus at the top, being the cipher of Christ. Having this sign (☧), his troops stood to arms. The enemies advanced, but without their emperor, and they crossed the bridge. The armies met, and fought with the utmost exertions of valour, and firmly maintained their ground. (tr. Alexander Roberts & James Donaldson)