Taking advantage of the involvement of the European powers in the First World War, Japan tried to make certain gains in China. She presented twenty-one demands to China, which accepted it entirely, would have made China virtually a protectorate of Japan.
Japan also occupied certain areas of China viz., Kiao Chou, Shantung and secured military position in Manchuria. In the midst of these developments China decided to join the war in the hope of getting a seat as an ally at the peace conference and thereby protecting her interests.
At the end of war China took part in the Paris Peace Conference, where she raised demand for the return of province of Shantung and cancellation of unequal treaties with foreign powers. But China could not achieve anything due to threat of Japan to walk out of the Peace Conference.
Ultimately, Japan was permitted to succeed to the German position in Shantung with the condition that Japan would restore the province to China through direct negotiation. However, China was relieved of all her obligations towards Germany under the Boxer Protocol.