Battle of Mount Badon
Battle of Mons Badonicus
Cad Mynydd Baddon

ca. 500 CE

A decisive battle between the Britons and Saxons; it's location and the warlords involved is something still debated.

It is first mentioned in Gildas' De Excidio Britonum, who says it occured in the year of his birth, assumed to be sometime around the year 500 CE. He places it forty-four years prior to his writing of the work, and as Maelgwn Gwynedd was still alive at the time of the writing, this would be prior to 547 CE, and so the Battle of Badon can not have happened later than 503 CE, though the Annales Cambriae incorrectly date it as late as 516. Unfortunately, Gildas doesn't say where Mount Badon is or who fought in the battle. Some believe that Badon is Bath, based on the Welsh (Baddon) and Saxon (Bažon) names for the city. However, this seems far too interior for the time period.

The Historia Brittonum says that Arthur lead the Britons: "In this engagement, nine hundred and forty fell by his hand alone, no one but the Lord affording him assistance." This is listed as his twelfth battle against the Saxons, and the most fearsome. Modern scholars believe that it was in fact Ambrosius Aurelianus who fought in the battle, not Arthur, and that the battle was against Aelle of Sussex.