Japan was already from 1902 in alliance with UK. Immediately after WW1 started UK officially asked Japan for assistance in destroying German navy around Chinese waters. Japan was more than ready to use this oportunity to gain more terriroty on the side of entente. Japan formally declared war on Germany on 23 August 1914. Already on 15 August 1914, Japan issued an ultimatum, stating that Germany must withdraw warships from Chinese and Japanese waters and transfer control of its port of Tsingtao to Japan. On 2 September 1914, Japanese forces landed on China's Shandong province and surrounded the German settlement at Tsingtao. During October, the Japanese navy seized several of Germany's island colonies in the Pacific - the Mariana, Caroline, and Marshall islands - with virtually no resistance. The siege of Tsingtao was not going so easy. German forces were giving quite some resistance even if they were completely surrounded by Japanese forces and some British forces. German defences were under constant bombardment, the Japanese moving their trenches further forward under the cover of their artillery. The bombardment continued for seven days. On the night of 6 November, waves of Japanese infantry overwhelmed the defenders. The next morning, the German forces, along with their Austro-Hungarian allies, asked for terms. Colony was formally taken over on 16 November 1914. After these victories Japan was soon looking for further expansion. UK and USA were ready to leave to the Japan former German colonies but specially USA was worried about further expansion in China. However Japanese government soon already in January 1915 pushed China with further demands. Because of USA oposition they left out demands for mixed police forces and demands for Japanese advisors in China government. But even without this Japan got many new concessions for its bussiness in China, Japanese citizens were allowed to buy land in some provinces and shinto missionaries were allowed to come in to the China. Japan during World War I - Wikipedia en.wikipedia.org Siege of Tsingtao - Wikipedia en.wikipedia.org History of diplomacy, book 2, written by a group of authors, published in 1947 in Ljubljana, pages 272-273 and 294-296.
