The British Army is the land warfare branch of the British Armed Forces. During World War I, British troops fought on the Western Front, the Salonika Front, the Italian Front, the Siege of Tsingtao, the East Africa Campaign, Gallipoli, the Mesopotamia Campaign, the Sinai and Palestine Campaign, the Caucaus Campaign and the Senussi Campaign. The British Army lost 673,375 killed and fielded more than four million men during World War I.