The 3rd Light Horse Regiment was a mounted infantry regiment of the Australian Army during the First World War. The regiment was raised in September 1914, and by December as part of the 1st Light Horse Brigade had moved overseas. The regiment only fought against the forces of the Ottoman Empire, in Egypt, at Gallipoli, on the Sinai Peninsula, and in Palestine and Jordan. After the armistice the regiment eventually returned to Australia in March 1919. For its role in the war the regiment was awarded nineteen battle honours.

The 1st Light Horse Brigade was a mounted infantry brigade of the Australian Imperial Force (AIF), which served in the Middle Eastern theatre of World War I. The brigade was initially formed as a part-time militia formation in the early 1900s in New South Wales and then later in Queensland. In 1914, the brigade was re-constituted as part of the AIF and was sent to Egypt. Forming part of the New Zealand and Australian Division, during the Gallipoli Campaign it served in a dismounted role between May and December 1915. After being withdrawn to Egypt it served in the Anzac Mounted Division from March 1916 as part of the Egyptian Expeditionary Force, taking part in the Sinai and Palestine Campaign until the end of the war. It was disbanded in 1919. After the war, the AIF light horse regiments were demobilised and disbanded; however, the brigade briefly existed as a part-time militia formation in Queensland until 1921 when its regiments were reorganised into cavalry brigades.