During 1940, the component units of the 9th Division were sent to the UK to defend it against a possible German invasion. After serving during 1941–1942 in the North African campaign, at the Siege of Tobruk and both the First and Second Battles of El Alamein, the 9th Division returned to Australia. In 1943–1944, it served in the New Guinea campaign and, during 1945, in the Borneo campaign. It was disbanded, following the end of the war, in early 1946.