Chengdu campaign
The Chengdu campaign was a campaign fought between the Communists and the Nationalists during the Chinese Civil War in the post World War II era and resulted in Communist victory and capture of Chengdu, national capital of the Republic of China and provincial capital of the southwestern Chinese province of Sichuan. The campaign was part of the Southwestern China campaign. Battle of Jianmenguan. Jianmen Pass (Jianmen Guan, 剑门关) was one of the key gateways of Sichuan. There are 72 peaks in the range and the only road going through the mountains was 50 metres wide. Whoever controlled this  2 km long stretch of the road controlled the gateway of Sichuan, and the Nationalists had built an elaborate system of bunkers in the area to strengthen its defense against the expected communist invasion. 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. Later, one of the battalions of the communist regiment was sent to outflank the defenders by traversing mountain terrain which was considered impossible by the local populace, including the defenders. The other two battalions of the communist regiment crawled forward along the ravine under the cover of darkness, and by 10:00 PM, they were within 50 metres of the pass. The attackers then launched their assault in darkness under the cover of heavy  fire, and with the help of the battalion that outflanked the defenders, they were able to cross the last ravine via a log and overwhelmed the defenders. With Jianmen Pass falling into enemy hands, the Nationalists had no choice but to retreat and abandon the town of Jiange (剑阁) in the afternoon of December 18, 1949. The Communists managed to capture over 300 prisoners-of-war and had all the remaining people killed in the fierce battle, and more importantly, the taking of Jianmen Pass (Jianmen Guan, 剑门关) secured the passage for the communists to invade deeper into the heart  of Sichuan.