William IV (1765–1837) was King of Britain and of Hanover from 26 June 1830 until his death on 20 June 1837. The third son of George III , William succeeded his elder brother George IV , becoming the last king and penultimate monarch of Britain's House of Hanover . William served in the Royal Navy in his youth, and was later nicknamed the "Sailor King". As his two older brothers died without leaving legitimate issue, he inherited the throne when he was 64 years old. His reign saw several reforms: the poor law was updated, child labour restricted, slavery abolished in nearly all of the British Empire , and the British electoral system refashioned by the Reform Act 1832 . Although William did not engage in politics during his reign as much as earlier kings, he was the last British monarch to appoint a prime minister against the will of Parliament. He granted his German kingdom a short-lived liberal constitution. William was succeeded by his niece Victoria in Britain and his brother Ernest Augustus in Hanover. ( Full article... )