The incumbent King of England, Henry VI, on the throne since 1422, was a weak, ineffectual and mentally unsound ruler, which encouraged the nobles to scheme for control over him. The situation deteriorated in the 1450s into a civil war between the supporters of his queen, Margaret of Anjou, and those of his cousin Richard, Duke of York. In 1460 the English parliament passed an act to let York succeed Henry as king. The queen refused to accept the dispossession of her own son's right to the throne and succeeded in raising a large army of supporters, who then promptly defeated and killed York in battle. The late duke's supporters considered the Lancastrians to have reneged on the parliamentary act of succession – a legal agreement – and York's son and heir, Edward, found enough backing to denounce Henry and declare himself king. The Battle of Towton was to affirm the victor's right to rule over England through force of arms.