The Japanese Empire entered World War I on the side of the Allied Powers. Japan declared war on Germany on August 23, 1914, following Britain's declaration of war on Germany two days earlier. Japan's main contribution to the war effort was the deployment of the Imperial Japanese Navy, which helped to maintain control of the Pacific Ocean and Indian Ocean. The Japanese Navy also helped to protect Allied shipping lanes from German U-boats. In addition, Japan sent troops to fight in Europe, where they participated in the Battle of Tsingtao and the Battle of Gallipoli.