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Why did George, duke of Clarence, join Warwick against Edward IV?

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Wars of the Roses Illustration depicting the Battle of Bosworth Field, with King Richard III on the white horse.

George, Duke of Clarence, joined Richard Neville, Earl of Warwick, against his brother King Edward IV primarily because he fell under the powerful influence of the Earl, who was increasingly frustrated by his loss of control over the King.1

The alliance was cemented by Clarence’s defiance of Edward IV’s authority, specifically through his unauthorized marriage to Warwick’s daughter, Isabel, in July 1469. This act of rebellion occurred as Warwick was actively organizing opposition to the King following a series of political disputes, including Edward’s secret marriage to Elizabeth Woodville and the King's rejection of Warwick’s diplomatic policies regarding France and Burgundy. By aligning himself with Warwick, Clarence became a central figure in the Wars of the Roses, participating in the conspiracies that eventually led to the temporary deposition of Edward IV and the restoration of Henry VI.12