What role did king bans of brittany and king bors of gaul play in the rebellion against arthur?

According to the Arthurian legends, these Kings become allies of King Arthur very early during the rebellion of vassal kings in Britain. They get killed in the battlefield fighting for King Arthur against the Frankish King Claudas, the leader of the rebellion. Their lands are taken by the latter as a prize of war.  

The role that King Bans of Brittany and King Bors of Gaul play in the rebellion against Arthur is that they were his allies in the battle of Bedgrayne.

King Bans, also known as the King of Benwick, was the father of Sir Hector de Maris and Lancelot. He was an ally of King Arthur and also the brother of King Bors.

King Bors was the king of Gaunnes or Gaul in the early period of King Arthur's reign. Both King Bans and Bors appeared in the 13th century Lancelot Grail cycle.

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