After Gao Buer sent 70,000 horses across the Jiangbei, Xiao Mo was ready to move and prepared to send troops to attack Gao Buer and unify the Jiangnan region. On the other side, Gao Buer was also preparing for the conquest of Xiao Miao, and asked people to send a letter to Feng An, and contacted and prepared to send troops at the same time, and attacked Xiao Mi from the north and south.

In terms of numbers, Xiao Mill has more than 400,000 troops, Gao Buer and Feng Ang together are less than 300,000, Xiao Milling has an advantage in troops, but most of them are defected by local separatist forces, and the internal relationship is relatively responsible, and it is not easy to coordinate operations, which gives Gao Buer an opportunity to take advantage of.

At the beginning of 620, Liu Wuzhou, who led the army south, was defeated by Li Shimin, and subdued Wei Chi Jingde, and took his hometown, Liu Wuzhou and Song Jingang fled to the Turks, and the latter two were killed by the Turks for some reason. Li Yuan crowned Li Shimin as the secretary of Yizhou Daoxingtai. In July of the same year, in order to contain Wang Shichong for Gao Fuji, who was preparing to attack Xiao Miao, Li Shimin led his army south to attack Luoyang.

Li Yuan also sent Li Xiaogong, who had already occupied Sichuan, to send 20,000 troops from Badong County to capture Yiling County in the upper reaches of Nanjun, threatening Nanjun and also pinning down part of Xiao Miao's troops.

In May, Gao Buer led 100,000 men and horses to Jiangxia to join Zhang Zhongping, so that Gao Buer's men and horses in Jiangxia reached 180,000.

In June, Feng Ang led Feng Zhidai and Feng Zhiyu to lead 20,000 men and horses from Gaoliang County to the north to attack Cangwu, Guiyang, Lingling, Hengshan and other counties.

Xiao Mo saw that the three groups of men and horses were attacking him, so he sent Wen Shihong to lead 40,000 troops to meet Li Xiaogong, and sent Lin Shihong and Shen Faxing to lead the old troops and sent some additional men and horses totaling 35,000 people to the south to meet Feng An. Xiao Mo brought 200,000 horses to guard Nanjun and Baling to face Gao Buer.

Gao Buer led Li Jing, Hongfu Nu, Zhang Zhongping, and Chen Guoren to command an army of 180,000 troops along the Yangtze River by land and water, entering Dongting Lake, and Xiao Mo also personally led an army of 200,000 to sit in Baling, leading the army to confront Baling County.

Gao Buer camp, Li Jing said: "The enemy army has more soldiers and horses than our army, but according to the report, most of them are rabble, and we can advance by water and capture Baling." ”

Gao Buer nodded and said: "What the general said is good, some time ago, Xiao Mill mobilized troops and horses because of the trembling of his subordinate generals, and suppressed a group of generals in the territory, and later in the name of recuperating the troops and recuperating in the people, he forcibly seized the military power of his subordinates, and there are contradictions inside, Xiao Milling quelled the rebellion of the brother of the general Dong Jingzhen, which created conditions for us to defeat Xiao Mill. ”

Everyone was still deliberating, and suddenly the guards came to report: "Tell the prince, Li Xiaogong sent someone to the camp, saying that there is something important to report." ”

Gao Buer glanced at the people in the camp: "Isn't this Li Xiaogong still attacking Yiling, sending people here will not be a defeat, ask us to reinforce him." ”

Then he turned to the guards and said, "Please come in." ”

Li Xiaogong's envoy entered the camp, and after paying homage, he said: "Tell the prince, my family's chief manager sent his subordinates to send a secret letter to the prince." ”

Gao Buer signaled him to come closer, took the letter from the messenger's hand, and opened it to see that he was a little dumbfounded, this is Dong Jingzhen's surrender letter to Li Xiaogong, originally from Dong Jingzhen's younger brother After Xiao Miao's was leveled, Xiao Miao's has always been uneasy about Dong Jingzhen.

Xiao Mo was originally a person who was generous on the outside but very suspicious in his heart, but on the surface he pardoned Dong Jingzhen because he did not participate in the rebellion, and secretly guarded against him.

A few days ago, Xiao Mo sent someone to Changsha and asked him to bring troops to Baling, Dong Jingzhen was afraid of being assassinated by Xiao Miao, so he wrote to Li Xiaogong and asked for the Tang Dynasty.

After Gao Buer handed the letter to Li Jing and the others, he said: "This is really an unexpected joy, but at the moment of the war, it is better to be cautious." ”

Chen Guodao: "Since the surrender of the minister, did not build an inch of merit, fortunately the descendants of the prince are especially good, the generals do not dislike, so that the ministers have settled down, now the war is imminent, the generals should not stay away, the ministers are willing to bring their own soldiers and horses to Changsha, if Dong Jingzhen sincerely surrenders and returns, if he has two hearts, the ministers will be captured and dedicated to the prince's account." ”

Gao Buer considered that if he occupied Changsha at this time, it would be a big blow to the enemy, so he ordered Chen Guoren to lead 40,000 naval troops to Changsha, and ordered each camp to stand still and wait for news from Changsha.

Before the soldiers and horses on Gao Buer's side moved, Xiao Miao, who heard that Dong Jingzhen was going to surrender to the Tang Dynasty, had already sent his subordinate general Zhang Xiu to lead 50,000 troops to surround Changsha.

Zhang Xiu has less than 20,000 soldiers and horses in his hands, so he is naturally not Zhang Xiu's opponent, so he can't stand in the city, stand on the city wall and talk to Zhang Xiu: "General Zhang, you and I were brothers in the past, why bother to force each other, you also know my hardships, originally I also had the plan to forget about life and death for Xiao Milling, but he couldn't tolerate people, so he was really forced to do it." ”

"Brother Dong, since you are ready to surrender to Li Tang, then we are no longer brothers, today do you open the city gate and take the initiative to surrender, or wait for me to kill and slaughter the city." Zhang Xiufei said proudly.

"Zhang Xiu, you are really arrogant, Changsha City is impregnable, although my strength is not as good as yours, but I stand in the city to hold on to you, what can I do?"

"In that case, then you and I will see the truth under our hands." Zhang Xiu immediately prepared to attack the city.

This is the subordinate said: "General, there is a large group of ships coming along the river in my rear, about 30,000 or 40,000 horses. ”

Zhang Xiu was shocked in his heart: "Can you find out where the soldiers and horses are?" ”

"Judging by the flag, it seems to be our people." Because Xiao Miao's soldiers and horses are miscellaneous troops, and the army has a variety of flags, Tanma just looks familiar, and he can't be sure who the person is.

Zhang Xiu ordered to suspend the siege of the city, and personally came to the rear army to check, and now the two sides can see the faces clearly with the naked eye, and the person who came was naturally Chen Guoren, he took the people out and ordered people to change the clothing of Xiao Mill's subordinate army, so he confused the enemy all the way, and it was easy to reach the city of Changsha through the check.

The two armies faced each other, Chen Guoren did not wait for the other party to react, and ordered ten thousand arrows to be fired together, Zhang Xiu saw that the other party's leading generals were very angry, but the banner was indeed his own people, and he was puzzled, so he was caught off guard by Chen Guoren, Zhang Xiu was also shot off the horse by random arrows, Zhang Xiu's army was in chaos, and it was too late to adjust the battle formation, and the people and horses on both sides stood together as soon as they touched.

Dong Jingzhen in the city saw the scuffle between the two sides outside the city, and was hesitating whether to go out of the city to help the battle, when he saw the young general under the city and said: "We are the military horses under the command of Li Xiaogong, and we are here to help you defend Changsha and quickly open the city to help the war." With that, he rode into the enemy's ranks.

Dong Jingzhen heard that Li Tang's military horses had arrived, although he also wondered how they came, but he also knew that the opportunity could not be missed, so he ordered all the soldiers and horses to open the city gate and kill them.

After Zhang Xiu was injured and fell off the horse, he was unable to organize the army, and saw that his side was attacked from both sides, and the formation was in chaos, so he fled into the mountains and forests with his cronies, and the commander fled, and the other horses were scattered by Chen Guoren and Dong Jingzhen in less than half a day, and many people also fled into the mountains.

After cleaning the battlefield, more than 20,000 enemy soldiers were killed, 20,000 prisoners were captured, and the rest of the horses were scattered. Chen Guoren did not send anyone to pursue the deserters, now holding Changsha is the key, once Gao Buer defeated Xiao Mill's main force in Dongting Lake, he can order people to send troops south from the sofa, and soon be able to pacify Xiao Mill's army.

Dong Jingzhen invited Chen Guoren to come to the Changsha County Guard's Mansion and said, "I don't know the general's surname." ”

Chen Guoren hugged his fist and said, "Chen Guoren." ”

"Oh, it turned out to be Lord Situ."

Chen Guoren was very disdainful of Dong Jingzhen, a person who betrayed the lord without a fight, and when he saw that the other party exposed his old bottom again, he said coldly: "Situ doesn't dare, it's just that the Chu Wangfu is joining the army, and the letter that Dong Junshou wrote to the chief manager Li Xiaogong before is it true?" ”

What's not true, your men and horses have taken advantage of the situation to occupy Changsha. Thinking so in his heart, Dong Jingzhen said in his mouth: "In the next sentence of the heartfelt words, I am attached to Li Tang, and I am willing." ”

Chen Guoren glanced at him and said, "It's not attachment, it's surrender." ”

Dong Jingzhen saw that Chen Guoren was aggressive, and he didn't like it in his heart, so he said coldly: "Yes, I am surrendering to Li Tang below, but Lord Chen joined the army in the Chu Wangfu and picked peaches halfway, I don't know if the King of Chu wants to be an enemy of Li Tang?" ”

"You don't have to worry about it, come here, ask Dong Taishou to go to Baling to see the King of Chu."

"Chen Guoren, don't deceive people too much, although your subordinates have a large number of generals, but the 20,000 soldiers and horses under your command are not vegetarians, you do this, regardless of the impact, are you not afraid of the mutiny of your subordinates?"

At this time, Dong Jingzhen's marching Sima hurriedly ran in and shouted: "Lord County Guard is not good, I have let the soldiers and horses go home by Lord Chen, and those who do not want to go home are left with four or five thousand people, all of whom have been absorbed by Lord Chen." ”

When Dong Jingzhen heard this, she glared at Chen Guodao: "Chen Guoren, you deceive people too much, I will go to Baling to see the King of Chu and see how you explain." "Then you have to go out.

Chen Guoren asked people to stop him, and said to the deputy general: "Leave me 10,000 soldiers and horses here, plus 25,000 newly recruited people, there is no problem in defending the city, you take the other people and horses, and by the way, escort Dong Taishou back to Baling to hand over the order to the prince." ”

The deputy general received the order, then led the army to set off, Xiao Mo lost 50,000 horses at a time, believing that before the victory with Gao Buer, he could not afford to send people to attack Changsha, so Gao Buer let Chen Guoren capture Changsha and temporarily garrison Changsha.

In order to strengthen the defense of Changsha, Chen Guoren reorganized Zhang Xiu's troops and Dong Jingzhen's men and horses, and gathered an army of 35,000 people. Gao Buer has always governed the army strictly, but he was sympathetic to the soldiers and treated them well, so he quickly returned the troops to his heart, and Chen Guoren also prepared a backhand to scatter them and put them under the jurisdiction of his own people.