From 1939 to 1945, Australia joined the Allies in fighting the Second World War. Australia’s armed forces fought in the Pacific, European and Mediterranean and Middle East theatres.^[100] The shock of Britain’s defeat in Singapore in 1942, followed soon after by the bombing of Darwin and other Japanese attacks on Australian soil, led to a widespread belief in Australia that a Japanese invasion was imminent, and a shift from the United Kingdom to the United States as Australia’s principal ally and security partner.^[101] Since 1951, Australia has been allied with the United States under the ANZUS treaty.^[102]