Prime Minister of Australia prime minister, otherwise William McMahon63. Robert Menzies was the oldest person to ever be prime minister, leaving office at 71 years old. The longest-serving Prime Minister was Sir Robert Menzies, who served in office twice: from 26 April 1939 to 28 August 1941, and again from 19 December 1949 to 26 January 1966. In total Robert Menzies spent 18 years, 5 months and 12 days in office. He served under the United Australia Party and the Liberal Party respectively. The shortest-serving Prime Minister was Frank Forde, who was appointed to the position on 6 July 1945 after the death of
British and French declaration of war on Germany propaganda to justify German expansionism). Two Western powers, the United Kingdom and France, gave guarantees to Poland that they would declare war if Polish independence came under threat, as presented in a statement to the House of Commons by British Prime Minister Neville Chamberlain 31 March 1939 (formalized by the British 6 April 1939; not ratified until 4 September 1939 by the French): Although they honoured these guarantees by declaring war soon after Germany's Invasion of Poland on 1 September 1939, and although the dominions of the British Empire quickly followed suit, so little practical assistance was given to Poland,