This theatre was the largest of all the theatres of WWI. It was made of four main campaigns. In the Sinai and Palestine Campaign, mainly British forces defeated the Turkish army. In the Mesopotamian Campaign, British forces, mainly the Army of India, also defeated the Turkish army. In the Caucasus Campaign, Turkey fought against the Russian Empire and other forces. In the Dardanelles Campaign the Turkish army defeated British forces, mainly colonial. There were also minor campaigns in Arabia and Southern Arabia, Aden, and Persia.