With the outbreak of the First World War the Otago Infantry Regiment was formed. Along with the Otago Mounted Rifles Regiment they served at Gallipoli in 1915, before being moved to the Western Front from 1916 until the end of the war. Eight hundred women formed the Otago and Southland's Women's Patriotic Association in 1914, which supported the overseas troops. Four thousand Otago men died during the war and when it ended and the troops returned, the Spanish flu struck between September and November in 1918.