Mons Badonicus

Battle of Badon
Part of the Anglo-Saxon settlement of Britain
Date Unknown, circa 500 Location Unknown, various locations possible Result Strategic British victory; Saxon expansion halted for many decades
Belligerents
Britons	Anglo-Saxons
Commanders and leaders
Unknown, possibly King Arthur	Unknown
Strength
Unknown	Unknown
Casualties and losses
Unknown	Unknown

The Battle of Badon (Latin: Bellum in monte Badonis or Mons Badonicus, Welsh: Cad Mynydd Baddon, all literally meaning "Battle of Mount Badon" or "Battle of Badon Hill") was a battle thought to have occurred between Britons and Anglo-Saxons in the late 5th or early 6th century. It was credited as a major victory for the Britons, stopping the encroachment of the Anglo-Saxon kingdoms for a period. It is chiefly known today for the supposed involvement of King Arthur, a tradition that first clearly appeared in the 9th-century Historia Brittonum. Because of the limited number of sources, there is no certainty about the date, location, or details of the fighting.

The earliest mention of the Battle of Badon is Gildas' De Excidio et Conquestu Britanniae ("On the Ruin and Conquest of Britain"), written in the early to mid-6th century. In it, the Anglo-Saxons are said to have "dipped [their] red and savage tongue in the western ocean" before Ambrosius Aurelianus organized a British resistance with the survivors of the initial Saxon onslaught. Gildas describes the period that followed Ambrosius' initial success:

From that time, the citizens were sometimes victorious, sometimes the enemy, in order that the Lord, according to His wont, might try in this nation the Israel of to-day, whether it loves Him or not. This continued up to the year of the siege of Badon Hill (obsessionis Badonici montis), and of almost the last great slaughter inflicted upon the rascally crew. And this commences, a fact I know, as the forty-fourth year, with one month now elapsed; it is also the year of my birth.

The Ruin of Britain is unclear as to whether Ambrosius is still leading the Britons at this point, but describes the battle as such an "unexpected recovery of the [island]" that it caused kings, nobles, priests, and commoners to "live orderly according to their several vocations" before the long peace degenerated into civil wars and the iniquity of Maelgwn Gwynedd. Passages of The Ruin of Britain that address Maelgwn directly are sometimes employed to date the work from accounts of the king's death by plague in the 540s, but such arguments ignore the obvious apostrophe employed in the passages and the possible years of composition involved in the final collected sermon.

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