William III of Orange was a Dutch prince who became King of England, Scotland, and Ireland in 1689. He was born on November 4, 1650, and was a key figure in the Glorious Revolution, which led to the overthrow of King James II. William's reign marked the beginning of constitutional monarchy in England. As a leader, William III was known for his military skills and his role in the War of the League of Augsburg. He worked to strengthen the Protestant cause in Europe and was married to Mary II, the daughter of James II. William ruled until his death in 1702.