From March 21 to 22, 1935, the Central Red Army crossed the Chishui River for the fourth time at crossing points such as Taipingdu and Erlangtan. The previous three crossings had drawn a large enemy force into southern Sichuan Province, allowing the Red Army to secretly retreat to Guizhou Province while the enemy was off guard. This crossing completely shook off the main enemy force, and the Red Army then crossed the Wujiang River to the south, advancing directly towards Guiyang, successfully breaking out of the enemy's encirclement. This was a decisive battle in the Long March, turning the tide from a passive to an active position.