護法運動
The Constitutional Protection Movement () was a series of movements led by Sun Yat-sen to resist the Beiyang government between 1917 and 1922, in which Sun established another government in Guangzhou as a result. It was known as the Third Revolution by the Kuomintang. The constitution that it intended to protect was the Provisional Constitution of the Republic of China. The first movement lasted from 1917 to 1920; the second from 1921 to 1922. An attempted third movement, begun in 1923, ultimately became the genesis for the Northern Expedition in 1926.