# Troops at York proclaim Constantine emperor, opening a civil war among tetrarchs Date: 306 ## The fact On 25 July 306, after Constantius Chlorus died at York, British and Gallic troops proclaimed Constantine emperor, against Galerius’s tetrarchic plan that Severus should rise. It is one event. ## Context Tetrarchic succession was already a war machine. Acclamation by soldiers is a coup-adjacent act. Later Christian vitae recode it as providence. [Constantine the Great](/people/constantine-the-great)’s documented role is bounded by other offices and collaborators named in the sources below. Sharing a field with them is not a reason to drop a documented act, and it is not a reason to assign later consequences done in the name after death. 25 July 306 is received accession at Eboracum after Constantius’s death. Lactantius and later Latin/English are the public carriers. He did not typeset New Advent. Named person as heading of the dated public instrument. Later editors, museums, printers, or offices share publication. Complex where later carriers date the row. ## Evidence and sources Livius and Britannica independently date the York acclamation; Lactantius’s later English is a hostile-to-persecutors, not a tape of the parade. Official or archival record: Livius — Constantine I (https://www.livius.org/articles/person/constantine-the-great/; Livius.org). ## Significance A military proclamation that starts years of Roman-on-Roman war is a [humanitarian-access](/drivers/humanitarian-access) harm. York is not the Milvian Bridge. Keep 312. A military proclamation that starts years of Roman-on-Roman war is a humanitarian-access harm. ## What is established and what is not Established: received chronology places the York acclamation on 25 July 306. Not established: a unique 306 casualty series in Britain. What would change the picture: a contradictory original with a different date or name, or a measured series that can be argued, with lag and alternatives, as a consequence of this instrument rather than of later institutions. The date is the date of this instrument, not a licence to back-date every later harm or benefit. Established here: a sourced, dated public instrument with a named contribution by Constantine the Great. What would change the picture: a contradictory original with a different date, signatory, or non-occurrence; a demonstrated forgery; or a measured series that can be argued, with lag and alternatives, as a consequence of this instrument rather than of other causes. They are not a public rating. ## People - Constantine the Great: https://factrail.ai/people/constantine-the-great ## Drivers - Humanitarian Access: https://factrail.ai/drivers/humanitarian-access ## Sources - https://www.britannica.com/biography/Constantine-I-Roman-emperor - https://www.livius.org/articles/person/constantine-the-great/ ## Methodology https://factrail.ai/methodology Canonical: https://factrail.ai/facts/co-york-civil-war-opening