The reason why the Qing army was able to enter the customs smoothly was thanks to the Ming Dynasty's Guanningjin Defense Line!
When the Manchus had eliminated all the opponents of the Central Plains and gained a foothold, they finally had time to sit down and examine the Ming Dynasty they had replaced. After all, he had obtained the right results from the corpse of the Ming Dynasty, and if he did not judge him, it would obviously be a bit unreasonable. However, because the Qing court was the party that picked peaches, it naturally had more or less 'colored vision' for the ming dynasty's characters and generals. At this point, it can be seen from the Qing Dynasty's evaluation of the ming generals at the end of the Ming Dynasty, and those Ming generals who could not beat themselves were mostly despised, and for those Ming generals who hurt themselves, although they were openly touted, they were actually ironic with knives and sticks
Among all the Ming Dynasty generals, the one who was held up and scolded the most fiercely, and the most representative one was Sun Chengzong. The evaluation of him by later generations of the Qing Dynasty can be described as very ''high'''!'' I felt that if the Ming Dynasty followed his advice and gave him all the power to let him do it, although it was not said that it would be able to recover the lost land, it would not be a problem at all to protect itself.
The Qing Dynasty can give Sun Chengzong such an evaluation, it can be said that in the entire Ming Dynasty except for the emperor, it is rare, and about this comment, many people say that the Qing Dynasty sincerely admired Sun Chengzong, for which I can only hehe, in fact, the irony of this sentence is much more than respect. The reason why the Qing Dynasty had such an evaluation was actually because Sun Chengzong did one thing, and this thing was civil engineering.
Sometimes I have always thought that Sun Chengzong is so keen on civil engineering, then his precious student Emperor Tianqi loves carpentry work, which is also understandable. Of course, this is actually not the point, the focus must go back to Sun Chengzong!
After the Ming Dynasty lost the entire Outer Liaodong After the patrol discord, the Ming Army could only shrink to Shanhaiguan generation to stick to it, and although Nurhaci was very bullish at that time, the Ming Dynasty was fighting with the Jiancheng Cannon of Shanhaiguan, Nurhaci definitely could not turn over much waves, and Nurhaci also understood, so most of what he fought was a lonely city outside Guanhai. After Sun Chengzong came, he sent home those officials who said that they would abandon Liaodong and rely on the Shanhaiguan defense line to wait for time, and then began to build the city wall to get a group of people to build an army to fight.
Soon, Sun Chengzong relied on the identity and relationship of the Emperor of the Heavenly Revelation to build a Guanningjin Defense Line that caused the Qing Dynasty a headache, rain or shine! Although this line of defense was later broken by more than half, most of it was a matter of personnel, not that the line itself was not good. In fact, it was still very useful, relying on this line of defense, Nurhaci was killed, and Huang Taiji could only fight with the defenders for a long time, or he had to run a long distance around this line of defense. Therefore, the people of the Qing Dynasty had a lot of opinions about this defensive line at that time, but only at that time, and when the Qing Dynasty sat firmly in the country and then looked back at this defensive line, they were very grateful for this line.
So why is this the case? The reason is very simple, if it were not for the existence of this defensive line, they would not know that they would have to wait until the Year of the Monkey and the Moon of The Horse!
Because since it is a civil engineering project, it is naturally very expensive. In addition to a group of soldiers and military generals, the Ming Dynasty spent up to 7 million taels of silver per year on this project to maintain it. At that time, the total revenue of the Ming Dynasty was only 3.8 million taels of silver. Coupled with natural and man-made disasters, sometimes the money is not collected, so that the average annual fiscal income will be at most 3 million taels of silver, and the fiscal revenue in these two years is not enough for the Kwantung gang to repair the city and spend military expenses, and the soldiers and peasants in the interior will be even more unhappy.
However, what is even more excessive is that the soldiers of the Guanningjin Defense Line are still very dissatisfied, the military salaries are not enough, they often make trouble, and once the income is high, when they look at the troops from the interior, they feel that people are coming to grab food and eat with themselves, and they often engage in exclusion and friction, so the centrifugal force of the army is getting bigger and bigger. In order to be able to maintain the Kwantung gang, the Ming Dynasty could only increase taxes on the interior, which Yang had turned a lot of people back. Therefore, the money problem surrounding the Guanningjin Defense Line eventually triggered a series of events that eventually smashed the Ming Dynasty to death. So, no money, what civil engineering do you do, no mess?
Reference: Draft History of the Qing Dynasty