Li Shi Min had achieved great results in his campaign against Goguryeo. In the 19th year of the Zhenguan War, the Tang army had conquered ten cities of Goguryeo and killed more than 40,000 people. In addition, the Tang army had also defeated the Goguryeon reinforcements, gaining a bountiful harvest. However, due to the severe losses and the freezing of his warhorses, Li Shimin chose to retreat and was unable to completely destroy Goguryeo. Even so, Li Shiming's campaign was still considered a success, and the gains far outweighed the losses.
Li Shimin's campaign against Goguryeo was a war that took place between the 18th year of Zhenguan (644) and the 19th year of Zhenguan (645). Li Shimin adopted flexible strategies and tactics, including water and land cooperation, siege of cities, elimination of reinforcements, and psychological attacks. He had conquered ten cities and killed 40,000 people. However, due to Goguryeo's stubborn resistance and harsh climate, Li Shimin was unable to conquer Goguryeo completely. Even so, Li Shimin's campaign had placed a huge military pressure on Goguryeo, weakening its national strength. All in all, Li Shiming had achieved a certain degree of victory in his campaign, but he had not completely conquered Goguryeo.
The war between Emperor Taizong and Goguryeo was a series of wars that took place between the 18th and 23rd years of Zhenguan. The Tang army had achieved many major victories in this war, breaking through many of Goguryeo's cities and beheading tens of thousands of enemies. However, the result of the war was unexpected. Li Shimin took the initiative to withdraw his troops after gaining the advantage. The specific reason was unknown. After that, the Tang Dynasty continued to harass Goguryeo, but they did not achieve their goal of destroying Goguryeo. All in all, the battle between Li Shiming and Goguryeo was still unclear and required further research and understanding.
Li Shimin's route to conquer Goguryeo was from Laizhou by sea to North Korea, and from Liaodong to Liaodong. The two armies converged at Youzhou. Then, Li Shimin personally led the army from Luoyang, passed through Ye County, and finally arrived at Youzhou.
Li Shimin's conquest of Goguryeo had resulted in a major victory. He had taken down many of Goguryeo's cities, wiped out a large number of Goguryeo soldiers, and seized a large number of spoils of war, such as horses, armor, and weapons. These results greatly weakened Goguryeo's strength, laying the foundation for the war to destroy Goguryeo. However, Li Shi Min did not completely conquer Goguryeo. Instead, he took the initiative to retreat. Thus, even though his campaign had yielded important results, he had not completely destroyed Goguryeo.
Li Shimin's expedition to Goguryeo was not completely successful. Even though he had obtained some victories in the battle and conquered ten cities, he ultimately failed to achieve his goal of destroying Goguryeo. When they attacked An City, they encountered strong resistance and were unable to conquer the city. Considering the harsh weather and the difficulty of logistics, Li Shimin had to order the retreat. Thus, although some results were achieved, overall, the Eastern Expedition was not a complete success.
Li Shimin's campaign against Goguryeo could not be simply defined as a victory or defeat. In terms of strategy, Li Shi Min did not achieve his final goal because he had not completely conquered Goguryeo. However, in terms of tactics, he had achieved a major victory, capturing ten cities and wiping out the main force of the Goguryeon army. He had also relocated a large number of Goguryeon residents. This war had dealt a devastating blow to Goguryeo, damaging their national strength. Therefore, it could be said that Li Shi Min had achieved victory in terms of tactics, but he had not achieved his goal in terms of strategy. Therefore, it could not be simply said that he had lost or won. Instead, it could be said that he had won half of the battle and lost half of it.
Li Shi Min's campaign against Goguryeo was not a complete failure. Even though he did not achieve a complete victory, the Tang army had achieved some results in the war and captured a portion of Goguryeo's territory. In addition, this war weakened Goguryeo's strength and laid the foundation for the unification of the Tang Dynasty. Li Shimin had demonstrated outstanding military skills and firm determination in the war, winning the respect of people at home and abroad. Thus, even though the outcome of the war was not ideal, it could not be said that Li Shimin's campaign against Goguryeo was a complete failure.
There was no clear number of soldiers Li Shimin had sent to conquer Goguryeo. However, according to the descriptions in [1] and [2], Li Shimin had brought at least 250,000 men with him to Goguryeo. The document [1] mentioned that Li Shimin led 60,000 troops in the vanguard of the army, while the document [2] mentioned that there were about 60,000 people led by Li Shiji and Li Daozong on land, and the total amount of troops led by Li Shimin was about 150,000 yuan. However, these numbers were not confirmed by other documents or provided more detailed information. Thus, the exact number of men Li Shiming had used to conquer Goguryeo was currently unknown.
Lee Zhi's expedition to Goguryeo resulted in the loss of more than ten cities, more than 50,000 casualties, and more than 70,000 captives. At the same time, the Tang army seized a large number of Goguryeo horses, armor, and weapons, severely weakening Goguryeo's strength. However, this battle did not completely destroy Goguryeo.
The battle of Tiger Cage Pass was the key battle in which Li Shimin defeated the two kings. In this battle, the Tang army led by Li Shimin defeated Dou Jiande's 100,000 reinforcements with just 4000 black armored soldiers and defeated Wang Shichong. This victory had laid the foundation for Li Shiming's unification of the world, making the unification of the Great Tang irreversible. The battle of Tiger Cage Pass was the pinnacle of Li Shimin's military career, and it was also the battle that made him a god. Although the specific process of the battle was unknown, Li Shimin showed a very high military level and implemented the strategy of attacking reinforcements. In the end, he successfully captured Dou Jiande and Wang Shichong. The victory of this battle allowed Li Shimin to obtain the exclusive position of General of Heavenly Strategy, which provided him with an excellent advantage in his later campaign to unify the world. The Battle of Tiger Cage Pass became a classic battle in the history of ancient China, and it was also an important milestone for Li Shimin to kill two kings in one battle.