XII - Robert Menzies
When Earl Page refused to serve under Menzies, he withdrew the support of the Country Party for the United Australia Party and so Menzies' first government was a minority government. Menzies first ministry included former PM Billy Hughes as Minister for Industry and future PM Harold Holt as Minister without portfolio assisting the two Ministers for Supply and Trade.
Menzies' and Page's hositilities continued but on the 3rd of September 1939, when Britian and France declared war on the Third Reich following its invasion of Poland on the 1st, Menzies also declared Australia to be at a state of war:
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.
- Robert Menzies, via ABC Radio, 3rd September 1939.
With this declaration of war, Earle Page offered the support of the Country Party to again form a formal coalition government but Menzies point blank refused. Even though the Country Party appointed Archie Cameron as its leader, no formal agreement or coalition was reached until the 14th of March 1940 following the loss of a by-election to a Labor candidate, on the resignation of Richard Casey, who became Australian Ambassador to the United States.
When Cameron agreed to Menzies' demand that the UAP as the major of the two coalition parties should have the casting vote in ministry posts, the formal coalition was agreed upon.
Menzies government was in trouble after three ministers were killed in an RAAF plane crash en route to Canberra and a shock 1940 election result in September which saw the UAP/Country coalition claim only 36 seats from 74 and thus fell 2 seats short of attaining majority government.
With the war intensifying, ALP leader John Curtin offered to form a unity-type government which Menzies refused but he did accept a proposal to set up an Advisory War Council in which both the government and opposition had equal representation.
Menzies left for four months to go to London to discuss strategy and the movements of Australian troops in Europe, as did Prime Ministers from Canada and New Zealand but back home with Arthur Fadden in charge as temporary PM, the domestic situation worsened and when Menzies returned to Australia, he found that he came under increasing pressure to resign, and so did so on 28th August 1941.
VII - Billy Hughes (again - kind of?)
Technically following the resignation of Menzies, Billy Hughes became leader of the UAP. His only action as leader was to convene a joint UAP-Country Party meeting to choose the next leader. The coalition chose Arthur Fadden who was sworn in as Prime Minister the next day.