York, Frederick Augustus, duke of, 1763–1827, second son of George III of England. In the French Revolutionary Wars he commanded (1793–95) the unsuccessful English forces in Flanders. Despite his incompetence in the field, he became a field marshal (1795) and commander in chief of the army (1798) and set about reforming army abuses at home. He led another disastrous expedition to the Netherlands in 1799. He resigned his command in 1809 after he was accused of selling army commissions through his mistress, Mary Anne Clarke. He was cleared and reappointed in 1811.