Schematic introduction: After the Red Army captured Zunyi, Chiang Kai-shek mobilized 400,000 troops to attack the Zunyi area, forming an iron barrel-like siege on the Red Army. Mao Zedong and others commanded the Central Red Army to adopt flexible strategies and tactics. From January 19, 1935 to May 9, 1935, they carried out the famous battle of crossing Chishui for the fourth time, that is, crossing Chishui once to get rid of passivity; crossing Chishui twice to avoid Attack the weak with real force; cross the Chishui River three times to mobilize the enemy to advance westward; cross the Chishui River four times to jump out of the encirclement.