Germany–Japan relations Kaiserliche Marine in and around Chinese waters. Japan, eager to reduce the presence of European colonial powers in South-East Asia, especially on China's coast, sent Germany an ultimatum on 14 August 1914, which was left unanswered. Japan then formally declared war on the German Empire on 23 August 1914 thereby entering the First World War as an ally of Britain, France and the Russian Empire to seize the German-held Caroline, Marshall, and Mariana Islands in the Pacific. The only major battle that took place between Japan and Germany was the siege of the German-controlled Chinese port of Tsingtao in Kiautschou
Asian and Pacific theatre of World War I on Germany. The German and Austro-Hungarian concessions in Tientsin and Hankow were occupied and their nationals detained. An even more serious plot was Germany's funding of the Constitutional Protection Movement, which geographically split China into two rival governments for eleven years. Asian and Pacific theatre of World War I The Asian and Pacific theatre of World War I consisted of various naval battles and the Allied conquest of German colonial possessions in the Pacific Ocean and China. The most significant military action was the careful and well-executed Siege of Tsingtao in what is now China, but smaller actions were also