Edward IV (1461-1470) and (1471-1483) won his crown at the Battle of Towton, aged only 18.
Edward was aided by his cousin Richard, Earl of Warwick, who was dubbed 'the Kingmaker'. Following the King's secret marriage to Elizabeth Woodville, however, they fell out and in 1470 the Earl deposed Edward and place Henry VI back on the throne.
Edward won his throne back in 1471 at the Battle of Tewkesbury. The Earl of Warwick and the Lancastrian Prince of Wales were both killed in the battle and Henry VI was taken to the Tower of London, where he was murdered.
The rest of Edward's reign was relatively peaceful and bought a bit of peace and stability to the land. Aged only 40, Edward suddenly became ill and died.