(1) Zhang looked down on Wu. Although Zhang is four years younger than Wu, his position in Beiyang system is much higher than Wu's. Zhang made a name for himself in Yuan Shikai's time and won Yuan's favor, ranking second only to Beiyang Sanjie (Wang Shizhen, Duan and Feng). Being able to compete with Cao Kun has always been a member of Cao Kun's army, and it was not known until Hengyang withdrew its troops.
(2) The strategy of controlling Wu with Cao was adopted, but whether the direct line is direct or not, as Cao Kun said, although relatives are not as close as subordinates, Cao Kun did not follow Wu Hui's lost support. Zhang has captured the northeast and northwest, but also wants to control the territory along the Yangtze River and the finances of the Beijing government, which makes Cao have no choice but to lean to it.
(3) Zhang Feng wavered between peace and war, hoping that Guangdong would make a northern expedition and Anhui would respond and enjoy the victory alone. Wu Luo regarded this war as a life-and-death struggle and did his best. Focusing on the eastern front, the unreliable Sixteen Divisions were placed in front of the western front, which led Duan to take the lead in the direct-Anhui war, and also led to the mistakes of the front-line uprising, which affected the whole line.
(4) Wu can only win the siege, but he can't lose it. Zhang can still return to the customs after losing, so he lacks the determination to win.