page_title: Constantine the Great and Christianity
section_title: Battle of Milvian Bridge
hierarchical_section_title: Constantine the Great and Christianity / Conversion / Battle of Milvian Bridge
context_page_description: During the reign of the Roman Emperor Constantine the Great, Christianity began to transition to the dominant religion of the Roman Empire. Historians remain uncertain about Constantine's reasons for favoring Christianity, and theologians and historians have often argued about which form of early Christianity he subscribed to. There is no consensus among scholars as to whether he adopted his mother Helena's Christianity in his youth, or, as claimed by Eusebius of Caesarea, encouraged her to convert to the faith he had adopted himself.
  Constantine ruled the Roman Empire as sole emperor for much of his reign. Some scholars allege that his main objective was to gain unanimous approval and submission to his authority from all classes, and therefore chose Christianity to conduct his political propaganda, believing that it was the most appropriate religion that could fit with the Imperial cult. Regardless, under the Constantinian dynasty Christianity expanded throughout the Empire, launching the era of State church of the Roman Empire. Whether Constantine sincerely converted to Christianity or remained loyal to Paganism is a matter of debate among historians.
context_section_description: Eusebius of Caesarea and other Christian sources record that Constantine experienced a dramatic series of events sometime between his father Constantius I's death in 306 and the Battle of the Milvian Bridge on 28 October 312. The battle secured Constantine's claim to the title of augustus in the West, which he had assumed unilaterally when his father died. According to the Life of Constantine, written after Constantine himself had died by Eusebius, who admitted he heard the story long after it had happened from the emperor himself, and who is not specific about when or where it occurred, Constantine saw a vision of a "a cross-shaped trophy formed from light" above the sun at midday.
  About the time of the midday sun, when the day was just turning, he said he saw with his own eyes up in the sky and resting over the sun, a cross-shaped trophy formed from light, and a text attached to it which said, "By this conquer." (τούτῳ νίκα) Amazement at the spectacle seized both him and the whole company of soldiers which was then accompanying him on a campaign he was conducting somewhere, and witnessed the miracle.
  — Eusebius of Caesarea, Vita Constantini, 1.28.2
  The Greek words "Ἐν Τούτῳ Νίκα" (in this sign, conquer) are often rendered in a Latin version, "in hoc signo vinces" (in this sign, you will conquer). According to Eusebius, Constantine also had a dream that same night. In the dream,
  the Christ of God appeared to him with the sign which had appeared in the sky, and urged him to make himself a copy of the sign which had appeared in the sky, and to use this as a protection against the attacks of the enemy.
  — Eusebius of Caesarea, Vita Constantini, 1.29
  Eusebius himself, writing his Church History shortly after 313, makes no mention of this story in that work, and does not recount it until composing his posthumous biography of Constantine decades afterwards. Lactantius, writing 313–15 and around twenty years before Eusebius's Life, also does not mention a vision in the sky. Instead, Lactantius mentions only that Constantine's dream took place on the eve of the climactic battle on the Pons Milvius across the Tiber, with the crucial detail that the "sign" was marked on the Constantinian soldiers' shields. According to Lactantius:
  Constantine was advised in a dream to mark the heavenly sign of God on the shields of his soldiers and then engage in battle. He did as he was commanded and by means of a letter X turned sideways, with the top of its head bent around (transversa X littera, summo capite circumflexo), he marked Christ on their shields (Christum in scutis notat). Armed with this sign, the army took up its weapons.
  — Lactantius, De mortibus persecutorum, 44.5–6
  It is unclear from these sources what Constantine saw and what was marked on his army's shields. Eusebius's description of the daytime vision suggests a cross-shaped (either Τ or †) symbol, whereas Lactantius's description suggests a staurogram (⳨), although the crux ansata (☥) or the Egyptian hieroglyph ankh (𓋹) have been proposed as interpretations as well. All of these symbols were used by Christians in the 3rd and 4th centuries. Eusebius concurs with Lactantius that a new device was added to Constantine's soldiers' shields, but does not connect this with the Battle of the Milvian Bridge, saying only that the "sign of the saving trophy" was marked, but not specifying when. Sometime after 317, Eusebius himself was permitted by Constantine, probably either in 325 or in 335, to see a standard that was made according to the emperor's dreamt instructions during the civil war. He described it as:
  A tall pole plated with gold had a transverse bar forming the shape of a cross. Up at the extreme top a wreath woven of precious stones and gold had been fastened. On it two letters, imitating by its first characters the name "Christ," formed the monogram of the Saviour's title, rho being intersected in the middle by chi ... From the transverse bar, which was bisected by the pole, hung suspended a cloth ... But the upright pole ... carried the golden head-and-shoulders portrait 
caption: The Emblem of Christ Appearing to Constantine, as imagined by Rubens (1622). Constantine's army sees a chi-rho in the daytime sky.
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