The Battle of Badon, also known as the Battle of Mons Badonicus, was purportedly fought between Britons and Anglo-Saxons in Post-Roman Britain during the late 5th or early 6th century. It was credited as a major victory for the Britons, stopping the westward encroachment of the Anglo-Saxon kingdoms for a period.
The earliest known references to the battle, by the British cleric Gildas, date to the 6th century. It is chiefly known today for the supposed involvement of the man who would later be remembered as the legendary King Arthur; although it is not agreed that Arthur was a historical person, his name first appears in the 9th-century Historia Brittonum, where he is mentioned as having participated in the battle alongside the Brittonic kings as a war commander, though is not described as a king himself. Because of the limited number of sources, there is no certainty about the date, location, or details of the fighting apart from the result being a victory for the Britons.