• March: "After distancing himself from the ailing Lyons (PM), Menzies resigned his Attorney-General and Industry portfolios and the deputy leadership of the UAP (held since 1935). He was objecting to the government's failure to implement its own National Insurance scheme in the face of opposition from Melbourne financial interests."
  The Macquarie Book of Events, 1983 p 347.
• Menzies is elected leader of the UAP after the death in office of Prime Minister Joseph Lyons, and following the nineteen-day caretaker Prime Ministership of Earle Page, Leader of the Country Party.
• 26th April: Robert Menzies becomes Prime Minister of Australia. James and Kate Menzies fly to Canberra on 3 May to attend the opening of Parliament with their son Robert as Prime Minister. For Mrs Menzies, aged 73, it is her first flight.

• In his first radio broadcast as Prime Minister, Mr Menzies said:

"I am a singularly plain man, born in the little town of Jeparit, on the fringe of the Mallee; educated at Ballarat, in a state school, and then by scholarship at a public school and Melbourne University. Apart from having parents of great character, intelligence and fortitude, I was not born to the purple." 

• Radio Broadcast
• TRANSCRIPT OF RADIO BROADCAST

DECLARATION OF WAR
3 September 1939
THE PRIME MINISTER ROBERT MENZIES

"Fellow Australians,
It is my melancholy duty to inform you officially that in consequence of a persistence by Germany in her invasion of Poland, Great Britain has declared war upon her and that, as a result, Australia is also at war.
No harder task can fall to the lot of a democratic leader than to make such an announcement.

Great Britain and France with the cooperation of the British Dominions have struggled to avoid this tragedy. They have, as I firmly believe, been patient. They have kept the door of negotiation open. They have given no cause for aggression.

But in the result their efforts have failed and we are therefore, as a great family of nations, involved in a struggle which we must at all costs win and which we believe in our hearts we will win."

• January 13: Bushfires devastate Victoria. The fires claim 71 lives on Black Friday when the temperature in Melbourne reaches 114°F.
• Page Government, (see Australian Prime Ministers) April 7: After the death of Lyons, Country Party leader Earle Page is temporary Prime Minister for 19 days until a new leader is chosen by the UAP.
• Menzies Government, (see Australian Prime Ministers) April 26.

"... Menzies won leadership with Hughes as deputy. Page attacked Menzies bitterly and resigned, taking the Country Party to the cross-benches."
The Macquarie Book of Events, 1983 p 348.

• Earle Page immediately attacks Menzies in parliament bitterly accusing him of disloyalty to Lyons and the government and suggesting Menzies was a coward for not serving overseas during WWI, although he was an officer in the Army reserve. After refusing to work with Menzies, Page takes the Country Party out of coalition with the UAP.
• September 3: Prime Minister Menzies declares that Australia is at war with Germany (Radio Broadcast). This reflects the attitude of the majority of Australians who considered that Britain's declaration of war on Germany automatically committed Australia to the conflict in their desire to provide traditional support for Britain.
• Prime Minister Menzies forms a War Cabinet on September 15 and estimates the government will spend £40,000,000 during the first year of the war.
• Conscription for Home Defence is announced.
• The first warplane made in Australia, the Wirraway, makes a successful maiden flight.

† Behind the scenes Australia's wartime decision-making 1939-45

• German troops occupy Czechoslovakia. On September 1 Germany invades Poland and annexes Danzig.
• September 3: Britain and France declare war; World War II begins. First enemy air raid on Britain September 6.
• The Spanish Civil War ends after the Nationalists capture Barcelona and Madrid surrenders. Britain, France and USA recognise the Franco government.
• USSR invades Finland and is expelled from the League of Nations; USA declares its neutrality.
• Britain introduces National Identity Cards and conscription.
• Discovery of nuclear fission of uranium by German physicist Otto Hahn. It led to the production of the atomic bomb and to a virtually inexhaustible source of energy.