The 9th (Wellington East Coast) Mounted Rifles was formed on March 17, 1911. They were mobilised during World War I as a squadron of the Wellington Mounted Rifles Regiment. They served in the Middle Eastern theatre of World War I and first saw action during the Battle of Gallipoli.As a part of the larger New Zealand Mounted Rifles Brigade (of the ANZAC Mounted Division) they went on to serve in the Sinai and Palestine Campaign.