In 1924, Tang Shengzhi aligned himself with northern warlords against the warlord controlling Guangdong, who was aligned with the Kuomintang. Peng conducted skirmishes along the Hunan-Guangdong border for nine months, but reorganized his battalion along pro-Kuomintang political lines in 1925. In late 1925, Chiang Kai-shek established the National Revolutionary Army (NRA) and led the Kuomintang to take control of Guangdong. Tang then aligned himself with Chiang and joined him in the Northern Expedition, an effort to unify China by defeating the northern warlords. The Hunanese army was reorganized, and Peng was promoted to the rank of major. When Wu Peifu invaded Hunan and occupied Changsha, Chiang sent the NRA to Hunan and began the Northern Expedition. Peng's forces then joined the Kuomintang, but Peng never joined it as a formal member. It was only after Peng joined the Kuomintang, in 1925, that he first heard of the Communist Party.