The Göktürk Campaign of 625

In the summer of 625 Ilig Khan invaded the Tang frontier from Lingzhou to Bingzhou.^[1] The Jiu Tang Shu says that he gathered more than a hundred thousand men and plundered Shuozhou.^[2] At Taigu he destroyed the army of the Tang commander Zhang Jin. He also took prisoner Wen Yanbo, Zhang Jin’s chief of staff.^[1] When the Tang armies came up, he asked for peace and withdrew.^[3]

The Tang on the eve of the war

In the first month of 625 the Göktürks and the Tuyuhun each asked for markets on the frontier. The emperor granted both requests.^[1] The Zizhi tongjian adds that China had lost its plough oxen in the years of disorder and now obtained them from the frontier peoples.^[1]

The Tang had disbanded their twelve armies when the empire was pacified.^[4] The Göktürk raids went on, so the emperor Gaozu set the armies up again. He wanted to train men and horses for a great blow against the Göktürks.^[1] In the sixth month Ilig raided Lingzhou. The court made Zhang Jin commander against him, with Wen Yanbo as his chief of staff.^[1]

Until then the Tang had written to the Göktürks as to an equal state.^[4] On the day jiachen of the seventh month Gaozu told his ministers that the Göktürks were greedy without end and that he would make war on them.^[1] From now on, he ordered, no letters were to be sent to them, only edicts.^[1] The Xin Tang Shu gives his reasons. He had treated the Göktürks generously while the empire was unsettled. Now that they had broken the agreement, he would destroy them.^[5]

The invasion

Ilig attacked Lingzhou and Shuozhou.^[5] Lin Mo, the governor-general of Daizhou, fought him at Xincheng and was beaten.^[4] The Tang then posted Zhang Jin at Shiling, Li Gaoqian at Dagu and Li Shimin, the prince of Qin, on the Puzhou road.^[4]

The Göktürks had crossed Shiling before Zhang Jin reached his post.^[5] The Zizhi tongjian follows them day by day in the eighth month: Bingzhou on renxu, Lingzhou on guihai, and the prefectures of Lu, Qin and Han on dingmao.^[1] Li Jing marched out by the Luzhou road, and Ren Gui held the Taihang mountains.^[4] Ilig himself plundered Shuozhou with more than a hundred thousand men.^[3]

Taigu

On the day renshen of the eighth month Zhang Jin fought the Göktürks at Taigu, and his whole army was lost.^[1] He escaped alone to Li Jing.^[3] The Jiu Tang Shu says that Ilig fell on Zhang Jin at Taiyuan. The Xin Tang Shu calls the place Dagu and adds that the governor-general Zhang Dezheng died there.^[6]

The Göktürks took Wen Yanbo prisoner.^[4] His office was close to the throne, so they questioned him about the strength of the Tang armies and their grain. He would not answer.^[1] They moved him to the Yinshan.^[1]

The withdrawal

Li Jing took the field, and Ilig could not advance. He camped at Bingzhou.^[2] He turned on Guangwu, where Li Daozong, the prince of Rencheng, beat him.^[5] In the Zizhi tongjian, Li Daozong, as governor-general of Lingzhou, beat the Göktürks on the day jiashen, after a raid on Lingwu.^[1] The Yukuk Shad plundered Suizhou.^[5] On the day dinghai Ilig sent envoys to ask for peace and drew back.^[1] The Jiu Tang Shu has Li Shimin march with an army as far as Puzhou. In its account Ilig left when Li Shimin came.^[2]

The fighting did not end with the peace. In the ninth month the Moheduo Shad took a county of Bingzhou. Lin Mo beat him.^[1] On the day bingwu Wang Junkuo beat the Göktürks at Youzhou and killed or captured more than two thousand of them.^[1] The Xin Tang Shu says of the raids of these years that the Göktürks went deep when they had their way, and asked for peace without shame when they were beaten.^[5]

Wen Yanbo

Wen Yanbo stayed with the Göktürks for more than a year.^[7] After the peace at the Wei bridge in the ninth month of 626, Taizong ordered him summoned back to court.^[7] In 630 he was made director of the Secretariat.^[8] In that office he carried the court debate on the surrendered Göktürks. He argued that they should be kept whole below the frontier.^[2]