House of York
William was summoned the Great Council of February 1458, (and indeed, he was instructed to stop foot-dragging and attend). He was one of the few nobles to fight first for the House of Lancaster, and then change to supporting the House of York. He fought at the Battle of Ludford Bridge in 1459 for Lancaster, and later fought in the Second Battle of St Albans (17 February 1461) as a supporter of the house of York. The Yorkists were commanded by his brother-in-law Richard Neville, 16th Earl of Warwick.