The Guominjun (simplified Chinese: 国民军; traditional Chinese: 國民軍; pinyin: Guómínjūn; Wade–Giles: Kuominchün), a.k.a. Nationalist Army, KMC, or Northwest Army (西北軍), refers to the military faction founded by Feng Yuxiang, Hu Jingyi and Sun Yue during China's Warlord Era. It was formed when Feng betrayed the Zhili clique during the Second Zhili-Fengtian War with the Fengtian clique in 1924. The Guominjun occupied Beijing, captured Zhili leader Cao Kun and expelled former Qing Dynasty emperor Puyi from the Forbidden City.
The Guominjun was very sympathetic to Sun Yat-sen's Kuomintang regime in Guangzhou, but due to geographic isolation they were independent of one another. The Guominjun was unusual for being an ideological army with its troops indoctrinated in Christian, socialist, and nationalist teachings. It also cared for its troops with welfare and education programs which was very rare at the time. This created a very determined, cohesive fighting force with high morale. One of its weaknesses was its small size and large territorial coverage, which meant that its troops were spread thinly.