In the late Ming Dynasty, Houjin fought many battles in the White Mountains and Black Waters, among which the more influential ones were the Battle of Salhu and the Battle of Ming Gyeonggi fought by Houjin, as well as the Battle of Chengzi with Korea. The first two battles were paid more attention because they were fought against the Ming Dynasty, and the Battle of Chengzi was often ignored because the Ming army was almost not involved.
However, in fact, the battle between the Qing Dynasty and Korea had a huge impact on the Ming Dynasty. Emperor Taiji was very proud of this battle, and he once triumphantly demonstrated to the Ming general Shen Zhixiang after the war: "Blessed by heaven, Korea has been pacified, mongolia and the kingdoms of Varkha are attached, and those who survive today are only the Ming kingdoms" (Records of Emperor Taizongwen of the Great Qing Dynasty)
Pre-war situation
As the eastern neighbor of the Later Jin Dynasty, the Joseon Dynasty was always loyal to the Ming Dynasty. Because the Joseon Dynasty has long been a vassal state of the Ming Dynasty, the cultural form of the Joseon Dynasty and the Ming Dynasty is consistent, and the scholars in the court believe in Cheng Zhu Lixue and adhere to the distinction between Huayi, that is, the Manchu Qing dynasty is barbarians, and the Ming Dynasty and Korea under the influence of Confucian culture are orthodox. During the Wanli Korean War, the Ming Dynasty sent troops to help Korea drive out the Japanese Wokou and further the relationship between the two countries.
Therefore, when the Ming Dynasty asked The Dprk to send troops to attack Houjin together during the Wanli Dynasty, the DPRK readily agreed. In the Battle of Salhu, both the Ming and Korean armies suffered a crushing defeat, and the King of Korea, Li Hun, fearful of Houjin, secretly contacted Houjin, and was deposed by the scholars on the grounds of "having a bad heart and losing money to Slave Yi". The new king, Li Qiang, pursued the banner of "Chongming Paijin" and resolutely drew a clear line with Houjin.
Although cooperation between Korea and the Ming Dynasty was no longer as close as before, in general, North Korea united with the Ming Dynasty against the Later Jin. For example, the Ming Dynasty sent Mao Wenlong to open a military base on the Korean territory of Lindao (PiDao), and The Dprk also did its best to fund it.
Due to North Korea's opposition and the presence of Phi Dao, Hou Kim always felt like a fish in his throat. Mao Wenlong's army was like a nail, nailed dead near Hou Jin's heart, posing a huge threat to it. Hou Kim has always wanted to take phi dao, but has not been able to do so due to the presence of North Korea.
Due to the constant threat of force by Emperor Taiji, North Korea was forced to reconcile with Houjin and pay tribute to Houjin. However, North Korea still submitted to the Ming Dynasty, regarded the Ming Dynasty as Zhengshuo, and paid tribute to Beijing every year.
The year after the Battle of Ding, Emperor Taiji asked Korea to provide ships to help Houjin in his crusade against the Ming Dynasty, but King Injo of Joseon replied: "MingGuo Yu Wu Father, who has been caressing me for more than two hundred years, now marches on my father's country, how can you help with a ship?" The ship can't be borrowed! (Records of Emperor Taizong of the Qing Dynasty)
The North Koreans did not help Hou Jin, and also sent troops to secretly assist the Ming army, which made Huang Taiji very angry. The situation at that time was that Houjin was getting stronger and stronger, and the Ming Dynasty was getting weaker and weaker, so it was inevitable that Houjin would attack Korea and pull out this nail.
North Korea is not unaware of this, but it also faces two difficulties. At home, due to long-term corruption, the DPRK is in chaos, the army is seriously understaffed, and the armament is seriously insufficient. Abroad, because North Korea was vassal to the Ming Dynasty and the Later Jin Dynasty and the Snake, the suspicious Chongzhen actually cut off the sale of Gunpowder for The DPRK, making the Korean firearms unable to function.
Battle of C
When Emperor Taiji wanted to establish the Qing Dynasty, he sent emissaries to Korea, and the letter included Mongols and others asking Korea to persuade Korea to enter as a "country of brothers", but Korea did not accept it, which led to Emperor Taiji's decision to conquer Korea. Although Korea had decided to make peace with the Qing Dynasty at this time, Emperor Taiji's determination to attack Korea had already been made. On the way to the Qing Dynasty by the Korean emissaries, the Qing Dynasty had already sent troops.
Emperor Taiji mobilized the Qing army, mongols, and Han Chinese to form a huge army, claiming to be 200,000, but in fact more than 100,000, of course, some scholars believe that the mobilization ability of the Qing Dynasty at that time could only mobilize tens of thousands. But no matter how many, even the Ming army could not resist the Qing army, and The DPRK was even more powerless to resist. The Ming Dynasty was no longer able to take care of itself at this time, and could only send a small navy, but was forced to turn back when it encountered a hurricane on the way.
Isolated and helpless, North Korea decided to take a defensive position and hold on to the city. However, Emperor Taiji took advantage of the small size and depth of the Korean territory and decided to drive straight in and take the capital of Korea.
In the Battle of Chengzi, some Korean troops also bravely resisted, but they were outnumbered and defeated, and the Korean Beijing division was surrounded. Upon hearing that the king was besieged and the barbarians invaded, the people of Korea gradually mobilized, and the troops of the king of Qin from all over the country also went to prepare to attack the Qing army from the rear and relieve the siege of the Beijing Division.
However, due to the emergence of traitors within Korea, the unfavorable situation of the war shook the will of Injo, so before the army and the people could mobilize, the Korean Capital Division surrendered Kaesong.
The Qing Dynasty imposed harsh conditions and demands on Korea, such as paying the Ming Dynasty seal and attacking Phi Dao. For North Korea, agreeing to this would mean completely subjugating to the "barbarians" and betraying the "orthodoxy." But now that North Korea has no choice, they are forced to fight for the Qing Dynasty.
With the help of North Korea, Huang Taiji soon captured Phi Dao. After pulling out this nail, Huang Taiji was refreshed, and in his eyes, the opponent was now only the Ming Dynasty.
The impact of the Battle of Czi on the situation was enormous. Korea's relationship with the Qing Dynasty changed from "brother" to "monarch", and it was forced to sever its clan relations with the Ming Dynasty. After subduing Korea and pulling out Phi Dao, the Qing Dynasty completely broke the unfavorable situation of being attacked on three sides, and it could finally free up its hands to boldly attack the Ming Dynasty.
The Qing Dynasty's plundering and exploitation of Korea provided supplies for the Qing army, and solved the situation of poor harvest and tight strategic materials of the Qing Dynasty. With armaments, the Qing army was naturally at ease in the face of the Ming army.
Although the Ming Dynasty did not have time to take care of itself at that time, Chongzhen was still a wrong move against the fall of Korea and the death of death. Without Korea and Phi Dao, the Ming Dynasty lost an arm, and this giant, who looked huge but was actually weak, completely lost the ability to fight against the Qing army. Emperor Taiji, on the other hand, attacked Korea and destroyed Phi Dao, clearing a major obstacle to entry and paving the way for the Qing Dynasty to unify the world.
Resources:
Records of Emperor Taizong of the Qing Dynasty