On October 21, 1950, Mao Zedong sent four telegrams to Peng Dehuai in North Korea in a single day, arranging the deployment of the campaign. In view of the fact that the "United Nations Army" was advancing northward and approaching the border between China and North Korea, in the early morning of October 21, Mao Zedong Telegrams were sent to Peng Dehuai and Deng Hua respectively, asking the volunteers to immediately change their combat plan and immediately deploy and annihilate several divisions of the South Korean Army that were advancing aggressively.

This episode mainly introduces that after the Chinese People's Volunteers secretly entered the DPRK, in order to win the first battle, Mao Zedong cautiously and carefully arranged the first battle. Under Mao Zedong's direct instructions, Peng Dehuai commanded the vanguard of the Chinese People's Volunteers to set up an ambush in concealment, defeated the "United Nations Army" in Wenjing, Huangcaoling, and Yunshan, and won the first battle of the War to Resist US Aggression and Aid Korea.