The Wars of the Roses - Battles. The rivalry between the house of York and the House of Lancaster started when King Richard II was overthrown by his cousin, Henry Bolingbroke, Duke of Lancaster, in 1399. But the Wars of the Roses actually began on May 22, 1455 with First Battle of St Albans when Richard, Duke of York and his ally, Richard, Earl of Warwick defeated the Lancastrians under Edmund Beaufort who was killed. York captured Henry VI.