In 1598 AD, the seven-year Wanli War to Aid Korea ended. The Ming Dynasty mobilized the domestic Qi Jiajun, Ma Jiajun, Navy Chen Lin, Deng Zilong and the main force of the Liaodong Frontier Army for its vassal state of Korea. These elite troops were carefully built by the empire.

In 1598 AD, the seven-year Wanli War to Aid Korea ( Imjin Japanese Rebellion ) ended. The Ming Dynasty mobilized the domestic Qi Jiajun ( Qi Jiguang remnants), and the Ma Jiajun ( Ningxia Magui Department), Navy Chen Lin, Deng Zilong Department, and the main force of the Liaodong Frontier Army ( Li Rusong Department), these elite troops carefully built by the empire, fought hard with Japanese samurai for 7 years on the narrow Korean Peninsula. Finally, It shattered Japan's ambition to invade Korea, but it also paid a heavy price. In particular, the Liaodong frontier army participated in the war throughout the entire war, and the losses were relatively more serious, which weakened the Ming Dynasty's military power in the Liaodong region. Just in the 18th year after the end of the War to Aid Korea (1616 AD), the Jurchen tribe in Liaodong The leader Nurhachi took advantage of the empty defense of the Ming army in Liaodong, openly resisted the Ming Dynasty and established his own political power, which was Hou Jin .

However, the Ming Dynasty did not gain nothing in the war to aid Korea. In particular, the responsibility of a great power and the humanitarian spirit shown by the Ming Dynasty strengthened the Ming Dynasty’s co-leader status in East Asia. It is indeed fun to joke about the big brother Ming, and the younger brothers are naturally happy to follow the Ming Dynasty. . Among them, the most loyal to the Ming Dynasty is North Korea ( Lee's North Korea ). For North Korea, the Ming Dynasty is its reborn parent. The King of North Korea has repeatedly publicized the kindness of the Ming Dynasty in public and trumpeted the relationship between the Ming Dynasty and North Korea. Not only is the relationship between monarch and minister as simple as that, but the relationship between father and son is so strong. Originally, North Korea was far away from the Central Plains and had little to do with the situation in the Central Plains. However, with the rise of the Jin Dynasty, especially when the Ming Dynasty lost the initiative in the Liaodong battlefield after the Battle of Saarhu in 1619, North Korea's strategic position came to the fore.

North Korea was on the flank and rear of Hou Jin, and was in contact with the garrison at Dongjiang Town ( Pidao ) of Mao Wenlong , and frequently harassed Hou Jin's rear. In particular, almost all of Mao Wenlong's food supply came from North Korea. In fact, during the Battle of Sarhu, North Korea also sent 15,000 soldiers to fight with the Ming army against the Jin army. However, the powerful combat power of the Eight Banners Army of the Later Jin caused the Ming army to be defeated miserably. The Korean army as a foreign aid also Almost the entire army was wiped out. After the war, Nurhaci focused his main attack on the Liaoxi Corridor, and had no time to take care of North Korea for a while. The Ming Dynasty actively contacted North Korea, which caused Hou Jin to fall into an unfavorable situation of fighting on two fronts for a long time and was unable to concentrate all its forces against the Ming Dynasty.

After that, Nurhaci was hit and killed by the Ming army's artillery under the Ningyuan city. Huang Taiji became the new leader of the Hou Jin Dynasty. Huang Taiji changed Nurhaci's strategic policy, temporarily stopped the attack on the Ming Dynasty, and began to attack the Ming Dynasty. Regarding the North Korean issue, at the same time, Huang Taiji also started to take action against Mongolia's Lin Danhan , which was really busy.

1627 In the first month of the year, Huang Taiji led the 40,000 Eight Banners eastward expedition to North Korea with Erbeile Amin as the main general and Beilezirharang as the deputy general. On the thirteenth day of the first lunar month, the Eight Banners Army crossed the Yalu River and besieged Yiju, an important town in northern North Korea. The North Korean defenders hurriedly responded to the battle. At the same time, Han Run, the internal Yingying, set fires everywhere, disrupting the defenders' defensive arrangements, and took the opportunity to open the city gate to welcome the Jin army into the city. In this way, Yiju fell, and the 10,000 Ming troops and 20,000 Korean troops in the city who participated in the defense of North Korea were completely wiped out. After the capture of Uiju, Amin stayed in Uiju with 8,000 cavalry, and personally led the main force to continue the attack south, defeating important towns such as Pyongyang and Seoul . The King of Joseon had no choice but to flee to Ganghwa Island (an island at the mouth of the Hanjiang River). Because the Jin army was not good at water warfare, they could only look at the river and sigh. Finally, after looting, the two sides concluded a brotherly alliance, and Huang Taiji deployed The first conquest of the Korean War came to an end. After the war, Kim took the initiative to withdraw from North Korea, and the two sides returned to the situation where the war started.

After the end of the first conquest of the Korean War, Huang Taiji directed his main attack on the Mongolian region in the west. The Mongolian Khan Lindan Khan at that time was an authentic descendant of Genghis Khan and had a high prestige in the Mongolian grasslands.After the rise of the Later Jin Dynasty, Lin Dan Khan shook hands with the Ming Dynasty and made peace. The two sides also concluded a military alliance against the Later Jin Dynasty. The Ming Dynasty provided Mongolia with a steady stream of materials and weapons, while Mongolia became an important northern barrier for the Ming Dynasty to resist the invasion of the Later Jin Dynasty. So As soon as Mongolia, Ming Dynasty, and North Korea formed a strategic encirclement on the west, south, and east of Jin Dynasty, Ming Dynasty's plan was not subtle. But Huang Taiji was not a vegetarian. Under Huang Taiji's attack, Lin Dan Khan was quickly defeated. Huang Taiji used marriage to incorporate the Mongolian nobles into the upper class of the ruling class of the Manchu . In this way, Mongolia became the leader of the Later Jin Dynasty. allies, Ming's northern defense line was opened. While Huang Taiji was actively attacking Mongolia, the Ming Dynasty was not idle either. The Ming army and the Korean army attacked Houjin from the south and east. This also indirectly caused Huang Taiji to be unable to eradicate Lin Dan Khan and had to watch Lin Dan Khan. Flee to Qinghai.

After solving the Mongolian issue, Huang Taiji once again put the North Korean issue on the agenda. This time Huang Taiji wanted to solve the North Korean issue in a package. On the first day of December in 1636 (at this time, Huang Taiji had changed the country name of Hou Jin to Qing Dynasty and the clan name Jurchen to Manchuria), Huang Taiji mobilized soldiers and horses from the Eight Banners of Manchuria, the Eight Banners of Mongolia, and the Eight Banners of the Han Army to gather together. The imperial commander of Beijing (Shenyang) personally marched, with a total force of 100,000, and almost all the generals who could fight were brought with him, such as Daishan , Dorgon , Duduo, Dorobele , Yue Tuo, Hauge, , Dudu, , etc., the lineup is extremely luxurious. Huang Taiji personally led the main force to attack from the front. After the army set off, it was overwhelming and successively captured Uiju, Guosan, and Pyongyang. The whole country of Korea was panicked. The King of Korea tried to lead his concubines and ministers to escape to Ganghwa Island again. However, based on the lesson learned last time, the Qing army had already sent cavalry to seize the Korean army's retreat channel to Ganghwa Island and cut off their retreat. The King of Korea could only After being able to escape to Namhan Mountain City, the Qing army surrounded Nanhan Mountain City and attacked day and night. In the dilemma of having no food inside and no reinforcements outside, the King of Joseon finally chose to surrender.

1 At the beginning of 1637, the king of Joseon, who was on the verge of despair, opened the gate of Nanhan Mountain City, went to Huang Taiji's station in person, and surrendered to Huang Taiji. Finally, Huang Taiji and North Korea reached an agreement, and North Korea paid tribute to the Qing Dynasty and severed ties with The relationship between the Ming Dynasty ; North Korea accepted protons from the Qing Dynasty; sent tens of thousands of troops to participate in the war against the Ming Dynasty; returned all refugees who fled to North Korea; and could not build defense measures and city walls without authorization.

From then on, North Korea was completely reduced to a vassal state of the Manchu Qing Dynasty, and it still didn't have much freedom. Huang Taiji attacked North Korea twice, especially the second personal expedition, which completely destroyed the military alliance between North Korea and the Ming Dynasty, causing the Ming Dynasty's plan to use North Korea to contain the Manchu Qing Dynasty in the rear to go bankrupt. The Manchu Qing Dynasty solved the instability problem in the rear area once and for all, and increased the In the previous military operation to conquer Mongolia, Huang Taiji completely shattered the Ming Dynasty's military alliance and was able to concentrate all its forces to attack the Ming Dynasty. Almost immediately after the second military operation to attack North Korea, Huang Taiji organized a large-scale attack on the Ming Dynasty. During the military operations in the hinterland of the Ming Dynasty, Huang Taiji bypassed the Guanningjin defense line that was heavily guarded by the Ming army, broke through the Great Wall from the Mongolian border and entered the Central Plains. This continued five times, annihilating a large number of Ming army's effective forces, and heavy It struck a blow to the Ming Dynasty's rule in the north and laid a solid foundation for its subsequent successful entry into the Central Plains.