[3] On 7 April 1939, with the storm clouds of the Second World War gathering in Europe and the Pacific, Joseph Lyons became the first Prime Minister of Australia to die in office, suffering a heart attack.

[7] In January 1940, Menzies dispatched potential leadership rival Richard Casey to Washington as Australia's first "Minister to the United States".

A new Coalition ministry was formed including the Country Party's Archie Cameron, Harold Thorby and John McEwen, as well as junior ministers Arthur Fadden and Horace Nock.

[7] In Europe, the Phoney War gave way to a succession of Allied defeats, as Germany overran the Low Countries, Norway and France.

Menzies called for an 'all in' war effort and with the support of Curtin, amended the National Security Act to extend government powers to tax, acquire property, control businesses and the labour force and allow for conscription of men for the "defence of Australia".

[7][9] With the 1940 election looming, Menzies lost his Chief of the General Staff and three loyal ministers in a Royal Australian Airforce crash at Canberra airport.

[3] The Labor Party meanwhile experienced a split along pro and anti Communist lines over policy towards the Soviet Union for its co-operation with Nazi Germany in the invasion of Poland.

Menzies banned the CPA after the Fall of France in 1940, but by 1941 Stalin was forced to join the Allied cause when Hitler reneged on the Pact and invaded the USSR.

[10] New Country Party leader Arthur Fadden became Treasurer and Menzies unhappily conceded to allow Earle Page back into his ministry.

In January 1941, Menzies flew to Britain to discuss the weakness of Singapore's defences and sat with Winston Churchill's British War Cabinet.

He was unable to achieve significant assurances for increased commitment to Singapore's defences, but undertook morale boosting excursions to war-affected cities and factories.

[3] After four months, Menzies returned to Australia to face a lack of enthusiasm for his global travels and a war-time minority government under ever-increasing strain.

In Menzies' absence, John Curtin had co-operated with Deputy Prime Minister Arthur Fadden of the Country Party in preparing Australia for the expected Pacific War.

With the threat of Japan imminent and with the Australian Army suffering badly in the Greek and Crete campaigns, Menzies reorganised his ministry and announced multiple multi-party committees to advise on war and economic policy.

Menzies announced to his Cabinet that he thought he should resign and advise the Governor General to invite John Curtin to form a government.