The 9th Division was a division of the Australian Army that served during World War II. It was the fourth division raised for the Second Australian Imperial Force (2nd AIF). The distinctions of the division include it being:

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.

The 9th Division was the fourth AIF division raised, being formed in the United Kingdom in late 1940. Initially it consisted of only two infantry brigades which had been formed in Australia and dispatched to Britain in order to defend against a possible invasion following the Fall of France—the 18th and 25th Brigades—under the command of Major General Henry Wynter. Later, the 24th Brigade was also assigned to the division.

In January 1941 Wynter became ill and was replaced as divisional commander by Leslie Morshead. By February 1941, 9th Division headquarters had been relocated to the Middle East. Around this time the divisions of the AIF underwent a reorganisation as the decision was made to send the more established brigades to Greece; as a result both the 18th and 25th Brigades were transferred from the 9th to the 7th Division. They were replaced by the 20th and 26th Brigades, both of which were considered to be less experienced and therefore less ready for action.

After completing its initial training in Australia, Great Britain and Palestine, the units of the 9th Division were sent to Cyrenaica in Libya in early March 1941 to complete their training and equipping as part of the garrison of this region. Short of equipment such as machine guns, mortars, anti-tank guns and carriers, most of the division's artillery and cavalry units did not accompany the infantry brigades to Cyrenaica at this time. The 20th Brigade was the first unit from the division to move, departing on 27 February. It was joined shortly by the other two brigades. It was during this time that the division suffered its first casualties when German bombers attacked the transport column in which the 2/13th Battalion was travelling, killing two Australians and wounding one other. By 9 March the 20th Brigade relieved the 17th Brigade from the 6th Division, along the Cyrenaican frontier.

By late March, it became clear that German-led Axis forces planned to launch an offensive in Cyrenaica. As a result, the 9th Division commander, Leslie Morshead, ordered the 20th Brigade to withdraw from the frontier, moving 160 miles (260 km) back towards Benghazi. The offensive began on 24 March, quickly forcing the British units along the frontier back as it drove towards Benghazi. Two days later the 26th Brigade took up positions in the west near the coast to support the 20th Brigade which was holding the pass at Er Regima. At this stage, the division's anti-tank troops were issued with captured Italian guns in order to make up the shortfall in British weapons.

As the Axis advance continued with German victories at Marsa Brega and Agedabia which threatened to outflank the units cut off in Benghazi, the 9th Division were ordered to fall back from their positions along the coast to the east to Derna. Lacking their own transport, they had to rely on that provided by other units and thus the withdrawal had to be undertaken in stages. In order to achieve this, the 2/13th Battalion was used as a rear guard and late in the afternoon of 4 April it undertook the division's first action of the war when the Germans attacked their positions in the Er Regima Pass. Supported by British artillery, the battalion, spread out across an 11-kilometre (6.8 mi) front, managed to delay a German force of about 3,000 personnel mounted in lorries and accompanied by armoured cars and tanks. Only lightly armed, however, they were unable to prevent the Germans from outflanking them, and gradually they were forced to pull back before. At 2200 hours, their transport arrived, and they were able to withdraw just as they were faced with encirclement. In this action, the 2/13th Battalion suffered five killed and 93 wounded or captured.

Two days after the action at Er Regima Pass, the 9th Division was ordered to fall back along the coast road towards Tobruk in what was later called the "Benghazi Handicap". Due to the speed of the Axis advance and the division's lack of transport, confusion reigned and part of the 2/15th Battalion, including most of its headquarters and its commanding officer, were captured.