In November 1937, when the Battle of Songhu was coming to an end, the Nationalist Government held a State Council meeting and determined that Japan was determined to capture Nanjing. For the sake of protracted war of resistance, it was decided to move the capital to Chongqing. After issuing the declaration to move the capital, Tang Shengzhi was appointed commander-in-chief of the Nanjing Garrison and organized the teaching corps, the 36th Division of the 78th Army, the 89th Division of the 71st Army, and the 88th Division of the 72nd Army. About 110,000 troops including the division, the 41st Division and the 48th Division of the Tenth Army and the 1st Battalion of the 8th Artillery Regiment remained in Nanjing. Wang Jingjiu's 87th Division was ordered to guard Guanghuamen, Hongzhuang Mountain, Tongjimen barracks and Yuhuatai area, and was responsible for blocking the invading Japanese troops on the Beijing-Hangzhou Highway. On the 10th, the main force of the Japanese army attacked Yuhuatai, Tongjimen and Guanghuamen simultaneously. The battle was very fierce. The 259th Brigade of Yi Anhua guarding Guanghua Gate resisted tenaciously without artillery support and the wounded could not retreat, and repeatedly repelled the crazy Japanese attacks. In the afternoon of that day, Japanese artillery fire blasted Guanghuamen, causing two gaps in the city wall. Japanese troops swarmed in. The situation was extremely critical. Chen Yiding was ordered to lead the officers and soldiers of the 261st Brigade to Tongji Gate and Guanghua Gate to reinforce the defenders on the city wall, and Yi Anhua's brigade was able to maintain frontal defense. At night, Chen Yiding's brigade selected death squads to fall down the city wall and eliminate all the Japanese troops lurking in the city gate cave and the Japanese troops entrenched in the Tongguang barracks. The front lines of Guanghua Gate and Tongji Gate were saved from danger. On the 11th, Japanese aircraft and artillery bombed heavily and most of the fortifications were destroyed. Brigadier Chen and Deputy Brigadier Sun Tianfang worked together and led the remaining troops of the 261st Brigade to fight tenaciously and defend the position at the cost of heavy casualties, preventing the Japanese army from advancing further. At noon on the 12th, the Japanese troops came like a tide. All friendly troops died heroically and Yuhuatai fell. Because Brigadier Chen lost contact with the division headquarters, he asked Deputy Brigadier Sun Tianfang to inquire with the neighboring brigade. Sun sent liaison staff Liu Ping to Ma Weilong Command Post to learn about the situation. After a while, Liu Ping came back and reported that the reinforcements of the 83rd Guangdong Army had evacuated Taipingmen and headed northeast, and Brigadier Ma also moved closer to the left. Deputy brigade commanders Chen and Sun Zheng looked at each other as if they were lost in the mist. After a long time, Brigadier Chen said to Sun Tianfang: "Tian Fang, I'd be very kind to you. Take some people with you and inspect the area near the left-wing railway in person to understand the situation and make a decision." Sun followed the instructions and went there. At about 0:00 on the 13th, I rode my bicycle back from Hepingmen and was informed that Nanjing had been lost, and the defenders retreated to Xianguan. Later, a meeting was convened for officers above the regiment commander, and the commander of the 260th Brigade was specially invited to attend and sign the resolution to show that everyone shared the responsibility of evacuating the position. The Battle of Nanjing is over. During the five-day battle, the superiors did not convene a meeting, deploy a battle strategy, or issue any battle or retreat orders. It could be described as a muddled defense battle.

Although Sun Tianfang led his troops to successfully break out of the encirclement, how could he feel at ease in the face of such a useless and tragic defeat?