The Jewish Legion was an unofficial name used to refer to five battalions of the British Army's Royal Fusiliers regiment, which consisted of Jewish volunteers recruited during World War I. In 1915, the British Army raised the Zion Mule Corps, a transportation unit of Jewish volunteers, for service in the Gallipoli campaign. Two years later in August 1917, the decision was made to raise an infantry battalion of Jewish soldiers which would be integrated into an existing British Army regiment.

The Gallipoli campaign, the Dardanelles campaign, the Defence of Gallipoli or the Battle of Gallipoli was a military campaign in the First World War on the Gallipoli peninsula from 19 February 1915 to 9 January 1916. The Entente powers, Britain, France and the Russian Empire, sought to weaken the Ottoman Empire, one of the Central Powers, by taking control of the Ottoman straits. This would expose the Ottoman capital at Constantinople to bombardment by Entente battleships and cut it off from the Asian part of the empire. With the Ottoman Empire defeated, the Suez Canal would be safe and the Bosphorus and Dardanelles straits would be open to Entente supplies to the Black Sea and warm-water ports in Russia.