In 655, Goguryeo and Baekje attacked Silla, but Silla could not resist and rushed to the Tang Dynasty for help. Emperor Gaozong of Tang sent the general Su Dingfang to lead the army into the Korean Peninsula, and Su Dingfang destroyed Baekje with the strategy of encircling Wei to save Zhao, and Goguryeo retreated without a fight under the intimidation of the Tang army. After Baekje was destroyed, Su Dingfang left Lang to garrison Baekje with Liu Renyuan and thousands of Tang soldiers, and led the main force to return to the dynasty. Buyeo Fukushin, the cousin of King Buyeo Yici of Baekje, saw the main force of the Tang army returning to China, thinking that there was an opportunity to take advantage of it, while summoning the old ministry to rebel, while sending people to the Uighurs to rescue.
Seeing that this was a good opportunity to infiltrate the Korean Peninsula, the Uighurs immediately sent tens of thousands of elite soldiers and more than a thousand warships to Baekje. In this way, Liu Renyan's situation was very dangerous, Su Dingfang left him too few troops, and the rebel army of a few thousand people dealing with Baekje was already stretched, so how to resist the tens of thousands of elites of the Uighur state? So while strengthening the city's defenses and making preparations for holding on, he sent people to ask Emperor Gaozong of Tang for help. Tang Gao sent Liu Renluo to lead 7,000 people as pioneers to the rescue.
For Liu Renluo, many people may be relatively unfamiliar. Compared with the famous warlords Qin Qiong, Luo Cheng, Pei Yuanqing and others in the early Tang Dynasty, Liu Renji's fame was much smaller, and he did not have many opportunities to perform. But when the opportunity came, he seized it keenly and made a name for himself in the ensuing battle. When liu ren rail led 7,000 reinforcements to the mouth of the Baijiang River, they encountered the main force of the Uighur state, when there were more than 40,000 elites of the Uighur state, and the warships were as high as a thousand, while Liu Ren rail only had 7,000 troops and only more than 170 warships.
Seeing that the Tang army had few soldiers, the Wei army immediately rushed forward, in a vain attempt to win more. However, Liu Renluo commanded Ruoding, and it took only half a day to completely annihilate the Wei army. The main reason for the total victory in the Battle of Baijiangkou was twofold: The first reason was that the Tang army was well equipped. Although the Wu army had more troops and warships than the Tang army, its individual equipment and the quality of the warships could not be compared with the Tang army, the Tang army warships were tall and strong, the soldiers were equipped with strong bows and crossbows, and many of the Wei army were killed by arrows during the upward attack; the second reason was that the tactics were appropriate. After the battle began, Liu Renluo commanded the Tang army to surround the Wu ships left and right, firing arrows while throwing fire, and for a time "the smoke rose in the sky and the sea was red", and more than 40,000 elite Wu troops were all buried on the seabed.
In the Battle of Baijiangkou, Liu Renluo won more with less, completely annihilated the elite of the Wu army, and thus entered the ranks of famous generals. After his class returned to China, Emperor Gaozong of Tang "deeply admired it, because of the sixth order of Chaojia (Liu) Ren Rail, he was teaching the history of Fangzhou's assassination and giving him a district of the capital." On the twenty-second day of the first month of 685, Liu Renji died. Wu Zetian stopped the dynasty for three days, posthumously gave kaifu Yi tongsan division, and the governor of the prefecture, accompanied the burial of Qianling, and gave his family a real seal of three hundred households. The advanced technology and strong combat effectiveness displayed by the Tang army in the Battle of Baijiangkou deeply stimulated the Uighur State, after which the Uighur State changed its name to Japan and continued to send Tang envoys to China to study, thus slowly rising and becoming an Asian power. For Liu Renluo, who annihilated tens of thousands of elite Japanese troops in the Battle of Baijiangkou, the Japanese not only did not resent him, but were grateful to him, knowing that without Liu Renluo, the Japanese might not realize their backwardness, nor could they send Tang envoys to China to study, so there would be no Current Japan.