The Central Plains War was a series of military campaigns in 1929 and 1930 that constituted a Chinese civil war between the Nationalist Kuomintang government in Nanjing led by Generalissimo Chiang Kai-shek and several regional military commanders and warlords who were former allies of Chiang. After the Northern Expedition ended in 1928, Yan Xishan, Feng Yuxiang, Li Zongren and Zhang Fakui broke off relations with Chiang shortly after a demilitarization conference in 1929, and together they formed an anti-Chiang coalition to openly challenge the legitimacy of the Nanjing government. The war was the largest conflict in the Warlord Era, fought across Henan, Shandong, Anhui and other areas of the Central Plains in China, involving 300,000 soldiers from Nanjing and 700,000 soldiers from the coalition.
The Central Plains War was the largest armed conflict in China since the Northern Expedition ended in 1928. The conflicts spread across multiple provinces in China, involving different regional commanders with combined forces of more than one million. While the Nationalist government in Nanjing came out victorious, the conflict was financially costly which had a negative influence on the subsequent Encirclement Campaigns over the Chinese Communist Party. After the entrance of the Northeast Army into central China, the defense of Manchuria was significantly weakened, which indirectly led to Japanese aggression in the Mukden Incident.