William III, also known as William of Orange, was the stadtholder of the main provinces of the Dutch Republic and the king of England, Ireland, and Scotland (styled William II in Scotland). As the sovereign prince of Orange from birth, he was educated in matters of state and religion. Later, he attended the University of Leiden and became deeply involved in political and military affairs. William was appointed stadtholder of the major provinces of the Dutch Republic in 1672, the same year he successfully led the defense against an invasion by French forces during the Franco-Dutch War. He married his first cousin, Mary Stuart, daughter of James, Duke of York (later King James II of England). When James II converted to Catholicism, concerns about the establishment of a Catholic dynasty alarmed the Protestant English populace. In response, Parliament invited William to intervene. This led to the Glorious Revolution (1688), during which James II was deposed. William and Mary were then jointly crowned as monarchs, marking the beginning of the shift from absolute monarchy to a constitutional parliamentary system in England. William ruled alongside Mary II until her death in 1694. He continued to reign alone until his death in 1702, leaving a significant legacy as a champion of Protestantism and parliamentary governance.