Historical background of Sun Wu's joint resistance to Cao Cao

The historical background is that at the end of the Eastern Han Dynasty, Cao Cao defeated Yuan Shao in Guandu, and then defeated Yuan Shao's three sons, Yuan, Yuan Tan and Yuan Shang, as well as the northern minority Wu Huan. The north of the Yellow River fell into the hands of Cao Cao, and there was only Marten in the northwest. Cao Cao ordered the governors to unify the whole country and send troops south. At that time, the governors south of the Yangtze River mainly included Jingzhou Liu Biao, Soochow Sun Quan, Zhang and Lu. At this time, Liu Bei was in Runan, defeated by Xinye and fled to Jiangxia. However, Jingzhou's military strength is not enough to resist Cao Cao. Plus Liu Biao was dead at this time, and the second son Liu Cong surrendered to Cao Cao under the guidance of Cai Mao and other capitulators. Liu Bei has lost the northern part of Jingzhou and can only persist in resisting in Jiangxia. Later, Liu Bei sent Zhuge Liang to contact Dongwu, and the two formed an alliance, rejecting Cao Cao with the natural barrier of the Yangtze River as a defense. Although Cao Cao is powerful, most of his troops come from Jizhou and Yizhou, which is embarrassing and highly valued. His own army is only100000. In addition, the northern military forces are not good at water warfare, and the Sun Liu family is United and sincere cooperation. There is a big victory in Chibi!