The theme of this question is the story of Wu Chu's "White Pony Battle" 506 years ago. Then why did Wu's 30 thousand army almost destroy the powerful Chu state? Everything happens for a reason, and in most cases, it is often a result. Let's analyze the reasons:

First, when Wu attacked Chu, the strength of Chu was not as good as before. 632 years ago, Jin Chu started the First World War in the Central Plains in Chengpu, Weiguo. Ignoring the warning of the King of Chu, Chu Lingyin Chengde (Yu Zi) led an aggressive army, which was annihilated by the Jin army. The Chu army was defeated and weakened, and Yu Zi hanged himself. History is called "the Battle of Chengpu".

Second, Wu is rising and Chu is declining. As early as Jin Chu's hegemony, Wu was good at water warfare, but not at land warfare. In order to contain Chu, Jin sent people to teach Wu the skills of land warfare, and Wu's military strength gradually became stronger.

Third, under the command of soldier Sun Wu, we adopted guerrilla tactics, in which the enemy advanced and we retreated, and the enemy stationed and disturbed us. Knowing that Chu could not be defeated head-on, Wu divided the army into three teams and attacked Chu in turn. As soon as the Chu army arrived, it retreated immediately, and the second team harassed it. So repeatedly. In this way, after six years, first, the Chu army was exhausted and wasted its national strength; The second is to paralyze the Chu army to a certain extent.

Fourth, seize the opportunity and work hard. Take it by surprise, attack it by surprise. 506 years ago, Chu attacked Cai, and Cai asked Wu for help. He Lv, the monarch of the State of Wu, and Wu Zixu, the doctor, knew that Chu was threatened by Qin Jin, and the internal situation was chaotic. At this time, it was a good opportunity to attack Chu, so he agreed to Cai's request and sent troops to save Cai. If you often play cards, Wu Jun will attack the hinterland of Chu, and Ma Pingchuan's Wan Basin is suitable for military action, so you have to go to Fangcheng, but Sun Wu chose to take three dangerous roads, but the Chu army neglected to defend the three customs, and Wu Jun soon broke through the three customs and quickly went south to the east bank of Hanshui River. Wu Jun won a winning streak in Lien Chan and kept attacking Ying Du, the capital of Chu, while Zhao Chu, the king of Chu, fled to Chu.