胶州湾租借地
Japan entered World War I on the side of the Allies in 1914, seizing the opportunity of Germany's distraction with the European War to expand its sphere of influence in China and the Pacific. Japan declared war on Germany on August 23, 1914. Japanese and allied British Empire forces soon moved to occupy Tsingtao fortress, the German East Asia Squadron base, German-leased territories in China's Shandong Province as well as the Marianas, Caroline, and Marshall Islands in the Pacific, which were part of German New Guinea. The swift invasion in the German territory of the Kiautschou Bay concession and the Siege of Tsingtao proved successful. The German colonial troops surrendered on November 7, 1914, and Japan gained the German holdings.