On this day 99 years ago, on August 15, 1926 (July 8, 1926 in the lunar calendar), the Battle of Nankou of the Northern Expedition ended. On August 15, 1926, the national army of the Northern Expedition retreated from Nankou and broke through to the northwest. The Battle of Nankou ended here. At the end of April, Wu Peifu, with the assistance of Zhang Zongchang's Zhilu coalition army, led the main force of the direct line to serve as the frontal offensive of Nankou. Feng Fang sent Wu Junsheng to lead Tang Yulin and Wan Fulin's troops to attack Duolun, take Zhangjiakou directly, and take Feng's back; Yan Xishan also sent troops out of Datong, cut off the retreat of the national army, and attempted to wipe out the national army in the Saibei grassland. But because the senior generals under Zhi and Feng had their own plans, the fighter jets were delayed, and Feng Jun launched the Jinbei War and threatened Yan Xishan. Wu Peifu and Zhang Zuolin were forced to clean up the interior first: free Jin Yunying and disarm Li Jinglin's department. Subsequently, Wu Peifu urged Tian Weiqin to issue a general offensive order, which was limited to three days to attack Huailai, but most of the Tianbu were Shaanxi troops, and they defected one after another. Zhang Zuolin was forced to re-locate the troops attacking the south entrance on July 19. Zhang Zongchang was the commander-in-chief of the former enemy, and the Feng and Lu armies were attacking the Qinglong Bridge at the south entrance. At the same time, Han Linchun was sent to lead the main force of the Fenghuang army from the east side of the south entrance through Yongning and Yanqing to insert behind the south entrance to launch an attack. When Wu and Zhang resumed their attack, the National Army had completed the purpose of blocking the westward advance of the Feng and Zhi armies, and retreated to Sui In August, when the National Army was in danger, Li Dazhao called Feng Yuxiang three times to return to China, and asked Yu Youren, an elder of the Kuomintang, to go to Moscow with Li's letter. After secret talks between Feng and Yu, Feng accepted Li Dazhao's strategic policy of "marching into the northwest, lifting the siege of Xi'an, sending troops to Tongguan, and supporting the Northern Expedition."