For Liu Yu, Xue Andu rebelled, attracting the Northern Wei army, although it was somewhat unexpected, but he was not too nervous about it. In his opinion, the army that had been sent earlier to show off its military might could be put to good use.
In December of the second year of the Tai Dynasty (466 AD, the first year of the Northern Wei Dynasty), the armies of Zhang Yong and Shen Youzhi had approached Pengcheng. The Song army began to be busy after resting and reorganizing the garrison in Xia, with Mu Zhi, the overseer of Yulin, leading 5,000 soldiers to garrison military supplies in Wuyuan, the general Xie Shanju of Longjun, leading 2,000 soldiers to guard Lüliang, and Zhang Zhang, a scattered horseman, leading 2,000 soldiers to guard Zhuyu and supervising the local people to hand over military food. Liu Song's army was fierce, and it was possible to defeat Xue Andu in one fell swoop to quell the rebellion.
But Liu Song did not expect that the enemy in front of him was not only Xue Andu. Wei Chiyuan (尉元) led the Northern Wei army to Pengcheng, and Xue Andu hurried out of the city to meet him. Wei Chiyuan then sent his troops to take Li Xuan and Xue An into the city first and control all the city gates. Subsequently, Kong Bogong was sent to lead an elite army of 2,000 people to patrol inside and outside the city, and Pengcheng was firmly controlled by Northern Wei.
Unbeknownst to the Song army, they launched an attack on Pengcheng that night, and Zhang Yong personally led an army to attack the southern gate of Pengcheng. However, at this time, Pengcheng's garrison was no longer something that Zhang Yong could deal with, and in the end he could not return to the camp without success, and could only lead his army back to the camp.
After repelling the first wave of the Song army's attack, there were also some problems inside Pengcheng. Because Wei Chiyuan despised Xue Andu, he was very rude to him. Xue Andu was very angry about this, and began to regret his surrender, so he planned to betray Northern Wei and return to Liu Song. However, Wei Chiyuan had already covered his eyes inside and outside Pengcheng, and he quickly noticed something strange and began to strengthen his vigilance.
Xue Andu did not dare to act rashly because of this, but Wei Chiyuan knew about this matter after all, which was still very unfavorable to Xue Andu. Xue Andu then began to save himself, bribing Wei Chiyuan while pushing the blame to his son-in-law Pei Zulong. Wei Chiyuan also did not want the situation in Pengcheng to make waves again, so he killed Pei Zulong and ended the matter.
After stabilizing the situation, Wei Chiyuan prepared to attack Liu Song's army. Considering that Zhang Yong occupied a dangerous terrain, it was not appropriate to confront him head-on. Wei Chiyuan then ordered Xue Andu and Li Xuan to hold Pengcheng, and he himself led an elite army to march, first attacking Xie Shanju, who was guarding Lüliang, and cutting off Zhang Yong's grain route. Xie Shanju fled to Zhang Yin, who was guarding JuJu, and the two of them went east to hold Wang Muzhi, who was guarding Wuyuan. Of course, Wei Chiyuan would not give them the opportunity to lead his army to capture Wuyuan, wang Muzhi's remaining base. Wang Muzhi suffered heavy losses and had to lead the remnants of his troops to Zhang Yong.
In the first month of the third year of the Tai Dynasty (467 AD, the second year of Northern Wei Tian'an), when he learned that his logistical supply line had been cut off, Zhang Yong and others, who knew that they were unable to fight any longer, decided to abandon the city and flee overnight. Who knew that the sky was not beautiful, the weather was very cold, and it caught up with the heavy snow under the sky, Surabaya was frozen, the ships could not move, Zhang Yong ordered his troops to abandon the ships and run south on foot. As a result, more than half of the soldiers froze to death, and their hands and feet were broken in 78 out of 10.
Wei Chiyuan took the opportunity to lead his army in pursuit, around the front of the Song army to intercept, Xue An was chased and killed in the rear, and defeated Zhang Yongjun in the east of Lüliang, killing tens of thousands of people, sixty miles away, the corpses overlapped, and the abandoned military supplies and weapons were uncountable. Although Zhang Yong's own toes were also frozen, it was fortunate that he escaped with Shen Youzhi. Liang, Southern Qin, shi yuan gongzu, and others were captured by northern Wei.
The news of the defeat of the army soon reached Jiankang, and Liu Yu hurriedly summoned his ministers to discuss countermeasures, but everyone had nothing to do, and Liu Yu saw Cai Xingzong and said with emotion: "In front of you, I am deeply ashamed." I really regret not listening to you in the first place. He then ordered Zhang Yong to be demoted to the position of General zuo, relieved of his official position, and ordered him to take up his current post in the name of Duke Zhenyang and return to Huaiyin to garrison.
In this battle, Liu Song suffered heavy losses, xuzhou, Yanzhou and Yuzhou Huaixi (Runan, Xincai, Nandun, Yingchuan counties) were occupied by Northern Wei, and Jizhou and Qingzhou were also in danger.
Unlike the previous Tuoba Tao period, which went south, this time the Northern Wei Did not retreat after burning and plundering, but was ready to rule these places. Wei Chiyuan, because after the Pengcheng army was in chaos, both the government and the people had exhausted their financial resources, so he specially requested the Northern Wei court to allocate grain stocks in the four prefectures of Ji, Xiang, Ji, and Yan, and to carry them along the Qing River with the nine hundred boats abandoned by Zhang Yong to help the residents newly incorporated into the territory, and the Northern Wei court approved it. Northern Wei's move also won the hearts and minds of the local people, but northern Wei's appetite would be limited to this?