In the late 1950s, the airspace of mainland China was frequently invaded by the enemy. The central government decided to purchase SAM-2 surface-to-air missiles from the Soviet Union and set up an air force surface-to-air missile unit, which marked the beginning of a new era of fighting against the enemy. A group of outstanding officers and soldiers from all over were ordered to join this mysterious unit code-named "543". Battalion Commander Xiao Zhanwu led a group of outstanding soldiers with their own characteristics to form the heroic Second Battalion, which has repeatedly made military exploits in the future. The whole battalion carried forward the fighting spirit of "one gun for the whole battalion", withstood the pressure of failed shooting, and shot down the RB-57D in one fell swoop, setting a record in the world's air defense history of shooting down high-altitude reconnaissance aircraft with surface-to-air missiles. At the most difficult moment of the army's construction, the enemy resumed its deep reconnaissance of the mainland. Faced with unfavorable factors such as professional and technical difficulties, uneven casualties, and shortage of missile spare parts, the Second Battalion resolutely took on the heavy responsibility of missile ambush and began arduous field operations. In the end, the entire battalion overcame numerous difficulties and shot down several enemy U-2 high-altitude reconnaissance aircraft in one fell swoop, creating an unprecedented brilliant record.