In May 1952, William Harrison served as the chief representative of the United Nations negotiating delegation. However, the United States took a firm stance on the prisoner of war issue and refused to explore any option other than voluntary repatriation, causing the negotiations to fall into an unprecedented dilemma.Especially on the 7th of that month, the negotiations came to a complete standstill.At the same time, the United Nations forces tried to weaken the morale of our troops on the front line through psychological tactics such as broadcasting, but they encountered a determined counterattack by the volunteer troops.

Chen Fenglou, a soldier of the 1st Company of the 15th Army, was furious about this and was eager to destroy the enemy with his own hands. However, the company commander Pi Lianlian rationally pointed out that the current priority is to consolidate the defenses.However, impulsively, Chen Fenglou still shot and killed an American soldier, and then continued to attack with cold guns and artillery, making the US 7th Division miserable.

Facing the well-equipped enemy forces, General Qin Jiwei made a decisive decision and asked the troops to build large-scale tunnels in the Battle of Shangganling area to strengthen defenses.However, many challenges were encountered during implementation.In order to solve the ideological concerns of the soldiers, Chief of Staff Zhang Yunyu cleverly proposed a tunnel digging competition between the Eighth Company and the First Company, which inspired both parties to work with unprecedented enthusiasm and devote themselves to tunnel construction.

In order to improve efficiency, Duan Xianfeng tried to introduce a new method of digging tunnels with explosives in the Eighth Company.Driven by this innovative technology, the Eighth Company was expected to win the competition, but unfortunately, a sudden bombing by US military enemy planes destroyed the newly completed tunnel, causing them to regrettably lose the victory.

Afterwards, Duan Xianfeng reported the situation to General Qin Jiwei, and Hu Mancang also admitted that he was too eager to advance and ignored the stability of the tunnel.At Qin Jiwei's initiative, the soldiers of the Old Eighth Company united as one and took a group photo full of optimism and resilience.

After unremitting efforts, the tunnel project was finally completed successfully, with complete internal facilities, including a medical room, storage room, weapons and ammunition depot, and a concealed cooking method.During the inspection by Wang Jinshan, deputy commander of the Third Corps, an unexploded aerial bomb fell on the Eighth Company position during the US military bombing.With his outstanding military skills, Duan Xianfeng successfully eliminated this time bomb and won high praise from Wang Jinshan.

After more than five months of hard work and construction, the 15th Army dug 325 tunnels more than 20,000 meters long in the defense area, as well as tens of thousands of meters of deer villages, trenches, traffic trenches and other defense facilities to build aA solid defense system with tunnels as the core was built, and it was connected with the tunnels of neighboring troops to form an “Underground Great Wall” across the defense zone.

After learning that the outpost was damaged, Cui Jiangong, commander of the 45th Division of the 15th Army, quickly ordered Liu Xiangyang, director of the Intelligence Division, to form a second echelon and rush up the mountain to rebuild the observation post.In view of the urgent task and the need for foreign language talents, intelligence staff officer Du Wenjin took the initiative to ask Ying to join.But on the way up the mountain, they encountered US military bombing of our military's communication lines.Although Duan Xianfeng organized people to avoid danger in advance, there were still Korean people who did not understand the language and ventured out. Du Wenjin's comrade unfortunately died during the rescue process. Despite all efforts, his life could not be saved.

In 1952, during the U.S. presidential election, the U.S. military's repeated defeats on the Korean battlefield became a powerful weapon for Eisenhower to attack Truman.He promised the American people that once elected president, he would immediately end the Korean War.At the same time, the new deployment of the US military on the front line aroused the vigilance of the Volunteer Army Command. After careful discussions, generals such as Deng Hua, Yang Dezhi, and Hong Xuezhi decided to speed up the formulation of a counterattack plan.

In October of the same year, Mao Zedong and Zhou Enlai approved the counterattack plan based on frontline battle reports, and emphasized the need to make full use of the advantages of tunnels to ensure the safety of the troops.General Qin Jiwei took the initiative to propose to Wang Jinshan a surprise attack on Highland 391 in view of the enemy's possible tactics of seizing the east and attacking the west, and received Wang Jinshan's firm support.