護法運動
In 1915 Yuan Shikai proclaimed the Empire of China (1915–1916) with himself as Emperor of China. Sun took part in the Anti-Monarchy war of the Constitutional Protection Movement, while also supporting bandit leaders like Bai Lang during the Bai Lang Rebellion. This marked the beginning of the Warlord Era. In 1915 Sun wrote to the Second International, a socialist-based organization in Paris, asking it to send a team of specialists to help China set up the world's first socialist republic. At the time there were many theories and proposals of what China could be. In the political mess, both Sun Yat-sen and Xu Shichang were announced as President of the Republic of China.