Background reason for the Sui and Tang dynasties to attack Goguryeo: In 427 AD, after Goguryeo established the capital at Pyongyang, it gradually became stronger and stronger, and since then it has continued to clash with the Sui and Tang dynasties frequently. The goguryeo kings vigorously advocated the strategy of fighting for peace. Their king's tyrannical conquests caused great harm to the ordinary people along the border line in the northeast region, causing the people in this area to live in poverty. More seriously, the rapid rise of Goguryeo made its ambitions grow, colluding with the Turks against the Central Plains Dynasty, making the borders of the northeast region more and more unstable.
Tang Taizong (picture from the network)
Emperor Taizong of Tang decided to send troops to Liaodong
After the Tang Dynasty ascended the throne of Emperor Taizong, Goguryeo still adopted hostile concepts toward him. In order to better defend the Tang army, they built many fortifications in Liaodong. Since the Liaodong region was originally China's territory, Li Shimin, who was brilliant and strategic, would never give it up to foreigners, so Tang Taizong decided to send troops to Liaodong.
The correct decision of the Tang Dynasty
However, in the early stages of the war, the Tang Dynasty did not achieve critical success. In order to defeat Goguryeo quickly, the Tang Dynasty started with its ally the Turkic Khaganate and destroyed the Turks in one fell swoop, leaving Goguryeo without its only support. Later, the Tang Dynasty formed an alliance with Silla and joined forces against Goguryeo, achieving many victories, and Goguryeo began to weaken gradually.
Tang Jun (picture from the network)
Since Goguryeo itself was on the Korean Peninsula, the Tang army would be exhausted after a long period of rapid marching, and it would become more than enough to resist Goguryeo. Therefore, it is an inevitable trend to improve the construction of the marine fleet, and after the construction, the marine fleet crosses the sea from Shandong Province and can immediately reach the capital of Pyongyang. By the time of Emperor Gaozong of Tang and Li Zhi, the Tang Dynasty gradually increased its full investment in the construction of the Tang Maritime Fleet, and soon established a powerful navy.
Tang Gaozong (picture from the network)
Emperor Gaozong of Tang won a great victory in his conquest of Goguryeo
Just as the Tang Dynasty was preparing to attack Goguryeo, there was good news: the yuan boy who had a high prestige in the Goguryeo army surrendered to the Tang Dynasty! It turned out that after the death of the Goguryeo courtier Yuan gai Suwen, a rift arose between his three sons, and the infighting was fierce. Once, his eldest son, Yuan, went to the front line to inspect military affairs, and was framed by his two younger brothers, saying that he had already surrendered to the Tang Dynasty. The Yuan boy was cornered and really surrendered to the Tang Dynasty.
Expedition to Goguryeo (picture from the Internet)
During his lifetime, Heungai Suwen was the only one in the Goguryeo kingdom, which made his family also have great power. The two younger brothers of the Yuan boy, Yuan Nan Jian and The Yuan Boy, have always wanted to squeeze out the big brother Yuan Boy, who, through the power they have mastered, forced the King of Goryeo to order the pursuit of his brother Yuan Boy who had fled. In this way, Yuan Boy was forced to join the Tang Dynasty camp.
With everything in place, the Tang army began its crusade against Goguryeo. Because Yuannan joined the Tang army, this enabled the Tang army to accurately grasp all the military deployments of Goguryeo, and it was also because of the leadership of Yuannan that the Tang army was invincible along the way.
More importantly, the Yuan boys had always had a high prestige in the Goguryeo army, and many troops were reluctant to resist after discovering that the Yuan boys were in the Tang army. Therefore, with the exception of a few stubborn and recalcitrant troops, the overwhelming majority of the other teams voluntarily surrendered their weapons, which made the war go very smoothly. With the cooperation of naval forces, the war soon achieved a comprehensive victory.
Conclusion
Later, the Tang Dynasty took control of the King of Goguryeo and, through his persuasion, submitted to many local forces that were originally pro-Tang. Subsequently, the Tang Dynasty set up a special agency to rule the region. In this way, the problem of Goguryeo's border problems that arose from the Sui Dynasty has since been perfectly and completely solved. To quell the border troubles of Goguryeo, the Tang Dynasty took two generations of emperors to achieve it, and it can be seen that its true strength in history cannot be underestimated! Do you have any comment on that?