In the second year of Jing Kang (1127), jin soldiers from the south captured the capital of the Northern Song Dynasty, Fenjing (present-day Kaifeng, Henan), and abducted two emperors of the Northern Song Dynasty, Song Huizong, Song Qinzong, and more than 3,000 imperial families, harem concubines, and courtiers, and the Northern Song Dynasty was destroyed.
In the four famous works "Water Margin", because the historical background of the book is exactly the events of the reign of Emperor Huizong of Song, when wang Jin and Lin Chong appeared in the book, they both used "800,000 forbidden army leaders", according to which we can guess that there were 800,000 forbidden troops in the Song Huizong dynasty.
So, when the Jin soldiers went south to attack the capital of the Northern Song Dynasty, where did the 800,000 forbidden troops go? Why not defend the capital?

Some readers may laugh at the author, why compare the number of troops rendered in a novel with the real events in history?
If the author told you that there were really "800,000 forbidden troops" during the Song Huizong dynasty, would you believe it?
First, let's briefly introduce what is the "forbidden army"?
During the Song Dynasty, the army was roughly divided into three types, one called the forbidden army, figuratively speaking, it was the elite troops directly under the imperial court; one was called the van army, which belonged to the local control of the troops; and the other was called the township soldier, whose status was lower than that of the van army, and it was even more incomparable with the forbidden army.
The Forbidden Army, according to the "Song Shi Bing Zhi" recorded: "The forbidden soldiers, the guards of the Son of Heaven, the palace front, the second division of the guards in short." His closest subordinates were zhubanzhi, followed by the head of the Imperial Army, the Imperial City Division, and the Qiji Temple. Yu was defended by the Beijing Division, ready to be requisitioned. Those who are outside, who are not stationed or tun berthed, are also grain and army. Taizu Jian's previous generation's loss, the elite of the Beijing Division, although it is known that the old system has been increased or lost, and the scale is far-reaching. ”
This passage summarizes the following three aspects of the Song Dynasty's forbidden army:
First, all the forbidden armies belonged directly to the imperial court and were directly controlled by the imperial appointed palace marshals;
Second, these armies were all elite troops of the imperial court, including the emperor's subordinates and the guards of the capital, as well as those in other places, who belonged to the forbidden army stationed outside the country, and took grain in the local area;
Third, in view of the phenomenon of self-respect and division of the feudal towns at the end of the Tang Dynasty and the Five Dynasties and Ten Kingdoms, Zhao Kuangyin, the grandfather of the Song Dynasty, concentrated all the elite troops in the capital to prevent local support from rebellion, and the scale of the forbidden army was very large.
Let's talk about whether the figure of "800,000 forbidden troops" is accurate or not.
The number of forbidden troops in the Song Dynasty was a variable figure, according to the "History of the Song Dynasty":
During the Kaibao period of Taizu of the Song Dynasty (968-976), the total number of troops in the Song Dynasty was 378,000, of which the number of forbidden troops was 193,000;
During the reign of Emperor Taizong of Song (995-997), the total number of troops in the Song Dynasty was 666,000, of which 358,000 were forbidden;
During the Reign of Emperor Zhenzong of Song (1017-1021), the total number of troops in the Song Dynasty was 912,000, of which the number of forbidden troops was 432,000;
During the reign of Emperor Renzong of Song (1041-1048), the total number of troops in the Song Dynasty was 1.259 million, of which the number of forbidden troops was 826,000;
During the reign of Emperor Yingzong of Song (1064-1067), the total number of troops in the Song Dynasty was 1.162 million, of which 663,000 were forbidden;
During the reign of Emperor Shenzong of Song (1068-1077), the number of forbidden troops was 568,000, and during the Yuanfeng period (1078-1085), the total number of forbidden troops reached more than 612,000.
According to the above data calculations, during the Song Huizong period, the forbidden army of the Song Dynasty was around 800,000, which should be similar, even if it did not reach 800,000, it should be around 500,000 or 600,000.
Let's talk about the era of the Song River Uprising described in the "Water Margin", according to the "Song Shi Zhang Shu Night Biography", the Song Hui Zong Xuanhe three years (1121), "The Song River rises from Heshuo, transfers to ten counties, and the officials and troops do not dare to baby Qifeng." ”
This record fully shows that the Song River Uprising broke out on the eve of the fall of the Northern Song Dynasty, which was the Song Huizong Dynasty, and the "800,000 forbidden army" claimed in the novel is basically consistent with the historical Song Dynasty forbidden army.
Then, as the army directly under the imperial court of the Song Dynasty, when the Jin soldiers went south to capture the city, where did this "800,000 forbidden army" go? Why not resist the Jin soldiers to defend the capital?
Before the fall of the Northern Song Dynasty, the Jin soldiers had besieged Fenjing twice, and in the first month of the first year of Jing Kang (1126), the Jin soldiers besieged Fenjing, and only because the main warrior Li Gang was reused, he made Fenjing safe and sound.
At that time, when the Jin army was retreating, the famous Northern Song general Zhong Shidao (the grandson of Zhong Shiheng) twice proposed to use the Jin army to withdraw its troops to cross the river, and the Song army went out to eliminate half of its remaining south bank, and crippled the most elite Eastern Route Army in the Jin Dynasty to eliminate the troubles.
As a result, the Song Dynasty's "surrender faction" swayed Song Qinzong's opinion, sent people to erect a large banner on the yellow river, and strictly ordered the Song army not to bypass the big banner to drive the Jin army, otherwise all would be executed.
When the Jin army first besieged Beijing, the total number of the Song army's original forbidden army and the Qinwang army that successively opened in the northwest reached about 300,000 people.
After the siege was lifted, none of these Song troops were resettled where they should have been: some were sent back to the northwest by demobilization, some suffered losses after participating in the Siege of Taiyuan, some were scattered on the south bank of the Yellow River, and some were dismissed by the surrender ministers Tang Ke and Geng Nanzhong for economic reasons.
In the winter of the first year of Jing Kang, the Jin soldiers made a comeback and besieged Beijing for the second time, when the Song army in the city was less than 70,000. The Qin Wangjun in various places had long been restrained by the orders of Tang Ke and Geng Nanzhong.
Although the "800,000 Forbidden Army" had some moisture, the main force of the Forbidden Army of the Song Army still had a fight with the Jin Soldiers at that time, but the representative figures of the main war faction, Li Gang and Seed Shidao, were deprived of their military power, and Song Qinzong blindly pursued the idea of "surrender faction", not allowing the Song army to fight with the Jin soldiers, and the Northern Song Dynasty did not perish, and there was really no reason!
This article is referenced from: "History of the Song Dynasty", "Cultural Code in water margin"