 After taking the city of Guangyuan on December 14, 1949, the communists decided that Jianmen Pass (Jianmen Guan, 剑门关) must be taken.The 540th Regiment of the 180th Division of 60th Army of the communist 18th Army Group was tasked with this job and after three days of forced march of more than 40 km in the mountain, the communist 540th Regiment reached Jianmen Pass.The communist 540th Regiment immediately launched its assault on the pass by first completely annihilating a company from the retreating nationalist 55th Division tasked to strengthen the defense.