徐世昌
After the end of the Qing Dynasty in 1912, Sun briefly entered a private business enterprise with Prince Qing, but was quickly drawn back into government as co-director general and later acting director general of the Customs Administration. On September 11, 1913, he was appointed to Premier Xiong Xiling's cabinet, and negotiated an agreement with Russia by which Russia recognized China's suzerainty over Outer Mongolia and China recognized Outer Mongolia's autonomy. When Xiong resigned in mid-February 1914, Sun became acting Premier until Xu Shichang assumed office in May. Sun served as minister of foreign affairs until January 1915, until he resigned in protest of Japan's Twenty-One Demands.