The reason why Jiaqing, who was very mediocre in all aspects, could become Qianlong's successor was mainly that Qianlong had no choice at that time.
In the winter of the thirty-eighth year of Qianlong (1773 AD), the Qianlong Emperor issued a secret edict about the establishment of the crown prince, and after several years of deliberation, the Qianlong Emperor finally decided to make the fifteenth son of the emperor Yongyan the crown prince.
Twenty-three years later, in 1796 AD, on the first day of the first lunar month of that year, the Qianlong Emperor officially proclaimed the Throne of Zen, and the fifteenth son of the Emperor, Yongyan, ascended the throne as the Jiaqing Emperor.

According to the records of historical materials and the evaluation of later generations, the Jiaqing Emperor, whether in terms of political means or in terms of government ability, his overall performance was really average, and the Qing Dynasty was also in his hands, and gradually began to decline.
Of course, the decline of the Qing Dynasty was not entirely due to Jiaqing, but his ability was generally an indisputable fact, so many people wondered why the Qianlong Emperor, who was quite shrewd, would choose such a mediocre successor.
In fact, there were many factors behind the Qianlong Emperor's choice of Jiaqing, and one of the biggest reasons was that the Qianlong Emperor did not have to be chosen, he had no shortage of sons who had the ability to stand out and were deeply loved by him, but for various reasons, Qianlong finally had to "pick a general among the lame" and chose Jiaqing, who was obedient, obedient, and very sensible.
Speaking of Qianlong's road to becoming crown prince, it was really a bitter tear.
The Qianlong Emperor had a total of seventeen sons in his lifetime, which is reasonable to say that there are many heirs, and if he is a crown prince, the choice should be relatively wide, but the actual situation is not so.
Why? Let's take a look at the qianlong emperor's road to becoming crown prince, and we will know what the reason is.
The Qianlong Emperor's first crown prince was his second son Ai Xinjueluo. Although Yonglian was said to be the second son, because his biological mother was empress Dowager Fucha of the Qianlong Emperor's Xiaoxian Chun, Yonglian was the eldest son of Zheng'er Bajing.
As we all know, in the period of feudal society, there was a long time, in the matter of establishing an imperial prince, it was all followed the principle of "standing a concubine and not standing long", including many dynasties before the Qing Dynasty, all of which were so on the matter of the crown prince, which has been a customary habit for thousands of years.
However, after the Qing Dynasty entered the Central Plains, some changes were made to this principle, after all, the Qing Dynasty originated outside the Guanwai, to put it bluntly, it was a nomadic people, so it was not so concerned about the customs and traditions of the Central Plains.
For example, after the death of the Qing Taizu Nurhaci, it was his eighth son Emperor Taiji who succeeded to the throne, and after the death of Emperor Taiji, it was his ninth son Fu Lin who ascended the throne, and after the death of the Shunzhi Emperor Fu Lin, he was also succeeded by his third son Xuan Ye, that is, the Kangxi Emperor.
The ascension of these emperors to the throne did not follow the principle of "standing up for a long time", of course, there are certain specific factors behind this, such as political struggle, etc., but in general, the tradition of having to establish the eldest son as the successor has been slowly diluted in the Qing Dynasty.
After the Kangxi Emperor succeeded to the throne, he once moved the idea of establishing the eldest son of a concubine, and the reason why he thought this way had a certain relationship with the degree of sinicization of him, and it was also inseparable from the fact that the eldest son of the concubine at that time, Yin Rong, was deeply loved by the Kangxi Emperor.
However, after he made Yin Rong the crown prince, for various reasons, he abolished Yin Rong's title as crown prince twice, and finally completely abandoned him, and before his death, he replaced the fourth son of the emperor, Yin Chan, as his successor, that is, the Yongzheng Emperor.
The Yongzheng Emperor was a person who had suffered greatly from the "Nine Sons and Concubines", so after he ascended the throne, in order to stabilize the situation, he creatively invented the method of secretly establishing a crown prince, in order not to let his sons repeat the mistakes of "brotherly cannibalism" in the past.
Yongzheng finally chose the fourth oldest Hongli as his successor, that is, the later Qianlong Emperor, and by this time, the concept of making the eldest son the crown prince was basically ignored.
However, after Qianlong ascended the throne, the first crown prince was still the eldest son.
There are two reasons for this, one is that Qianlong likes to emulate his grandfather Kangxi, so qianlong wants to be perfected here because of the regret that Kangxi once failed to make the eldest son of Qianlong the ultimate successor, and second, it is Qianlong's eldest son Yonglian, who can be said to have pinned most of Qianlong's feelings.
First of all, YongLian's birth mother was Qianlong's favorite empress Fucha, and the deep affection between the two was so deep that there were many relevant records in the history books that after the two of them got married, they were almost tired of being together, and even after Qianlong ascended the throne, they still had a deep affection for the Fucha clan.
On the basis of this feeling, the love crystal of the two People, Yonglian, came to the world, when Qianlong had not yet ascended the throne, he was still just a prince, and in order to highlight the importance attached to this child, the Yongzheng Emperor, as his grandfather, personally named him Yonglian, and the word "Lian" in it was the meaning of the Inheritance Instrument.
To put it bluntly, at that time, the Yongzheng Emperor and Qianlong had already designated Yonglian as the future crown prince from their hearts, and in the first year of Qianlong, that is, the year when the Qianlong Emperor had just ascended the throne, they wrote a secret edict and designated Yonglian as the crown prince.
But this nail-in-the-coffin thing happened soon after, when Yonglian grew up to be two years old, just because he was infected with a wind chill, he actually died prematurely.
At this point, Qianlong and Fucha were extremely sad, although Yonglian's funeral was handled extremely solemnly, and he also became the first crown prince in the Qing Dynasty to have his own cemetery, but what about this? After all, no one was gone, and the days to come were still long, so soon after the funeral, the Qianlong Emperor began to look for a new candidate for the crown prince.
The second successor the Qianlong Emperor was looking for was his seventh son, Yong Chun.
Yong Chun and Yong Lian were brothers of a mother, and their birth mothers were both empress dowagers, and like Li Yonglian, the Qianlong Emperor was based on the principle of "loving the house and Wu" and was also preparing to make Yong Chun crown prince.
However, before the Qianlong Emperor could write the edict, this Yong Chun died of chicken pox in the following year of his birth.
Successive blows not only made the Qianlong Emperor very sad, but also made the Fucha clan heartbroken, and not long after Yong Zhen's early death, the Fucha clan died of illness.
At this point, after the death of Fu Chashi, the Qianlong Emperor's idea of making a concubine as the crown prince was completely shattered, so he could only turn his eyes to other princes, and it was this turn that gave Jiaqing a chance.
However, at that time, Jiaqing was still far from entering the eyes of his father Qianlong.
If you calculate according to age, among the living princes at that time, the eldest son of the emperor, Yong Huang, was the oldest, and now the concubines are all dead, so his opportunity comes, it can be said that Yong Huang at that time was a person with a larger winning margin, and he had a great chance of becoming the new prince.
But in the end, Yong Huang still rubbed shoulders with the opportunity and was excluded by Qianlong, because fucha had just died of illness at that time, and the Qianlong Emperor was full of sorrow to prepare a funeral for him, and as a result, during the funeral, Qianlong saw that the eldest son Yong Huang and the third son Yong Zhang's expression was not sad enough, so in a rage, he beat up his two sons and announced on the spot that they were not qualified to succeed to the throne.
Regardless of whether Qianlong was too sensitive or not, the final result of the single incident was that these two people could no longer be made crown princes.
Up to that time, four of Qianlong's sons had either died prematurely or because they had made mistakes and lost the qualification to succeed to the throne, and the old fourth Yongjun had been passed on, so the first in Qianlong's heart was the fifth son of the emperor, Yongqi.
Yongqi is the "Five Brothers", he is the same as the TV series, intelligent in nature, and erudite, so he gradually attracted the attention of Qianlong, and an incident that happened in Qianlong in the twenty-eighth year of Qianlong made Qianlong firmly designate Yongqi as the candidate for the crown prince.
In May of the twenty-eighth year of Qianlong, the Yuanmingyuan suddenly caught fire, at this time the Qianlong Emperor was resting in the Yuanmingyuan, after learning that his father was surrounded by fire, Yongqi risked his life, broke into the Yuanmingyuan alone, and desperately carried Qianlong out.
Because of this incident, Qianlong was impressed by this son who risked death, and soon after, he promoted Yongqi to the title of Prince of Rong, which was the first person in the Qianlong Dynasty to be made a prince while he was alive.
As a result, only a year after Yongqi became prince, he died of a sudden illness at the age of twenty-six.
At this time, it was already thirty-one years of Qianlong, and as of this year, in addition to the princes who had lost their inheritance qualifications because of mistakes, there were many princes who died in infancy or in their youth due to illness, and there were only five princes who were alive and qualified to inherit.
The five princes were Yongxuan, the eighth son of the Emperor, Yongxuan, the eleventh son of the Emperor, Yongxuan, the twelfth son of the Emperor, Yongxuan, the fifteenth son of the Emperor, and Yongxuan, the seventeenth son of the Emperor.
Although the five are a little less, there is still room for choice, but among these five princes, the first one to be excluded is the eighth son of the emperor, Yongxuan.
Why? It was because this Yongxuan was a person with a physical disability, and with this obvious defect, no matter how strong the ability was, it would definitely be ruled out.
The second one excluded was the seventeenth son of the Emperor, Yong Xuan, who and the later Jiaqing Emperor were brothers of a mother, both of whom were Xiaoyi Chun Empress Wei Jia, and the reason why he was excluded was simply because he was too young at the time, or a yellow-mouthed child, so naturally it was not in the scope of consideration.
In this way, the Qianlong Emperor could only choose three princes, namely the eleventh son, the twelfth son, and the fifteenth son.
Among these three, the most competitive advantage and the upper hand in all aspects of ability is the twelfth son of the emperor, Yong Xuan, whose advantage is that his birth mother was the then empress Nala clan, and the empress of the Nala clan was canonized again by the Qianlong Emperor after the death of the Fucha clan, so after the canonization of the Nala clan, her son was in a sense a concubine.
That is to say, the twelfth son of the emperor, Yong Xuan, was the highest among several princes at that time, and he should also become the crown prince the most, at the same time, his ability in all aspects was relatively good, and Qian Daxin, a historian in the Qing Dynasty, who had served as a lecturer of Yong Xuan, evaluated his student as "pure talent and outstanding nature".
However, in the end, Yong Xuan was still excluded by Qianlong, mainly because in the thirtieth year of Qianlong, Yong Xuan's biological mother Nala clan accompanied Qianlong on a southern tour, but for some reason, Qianlong sent someone to send the Nala clan back to Beijing on the southern tour, and a few months later, he recovered the treasure of the Nala clan empress.
This means that the position of queen of the Nara clan was abolished, and there was a fire at the city gate, which affected the pond fish, and it was precisely because of the mother's loss of favor, yong xuan, who was the son of man, naturally inevitably suffered and was excluded.
At this time, only two princes were left to choose, and after comprehensive consideration in all aspects, the Qianlong Emperor finally chose the fifteenth son of the emperor, Yongyan, which was the future Jiaqing Emperor.
The reason why Jiaqing was chosen is because he is very balanced in all aspects, although there are no outstanding advantages, but fortunately, he can develop in a balanced way.
For example, literary attainments, Jiaqing in his youth, is famous for "diligent study", and his academic performance is quite good, and he can even achieve the degree of "helping the pen to stand up", of course, he is not the only one among the princes who can reach this level, but Jiaqing is not only very good at literary attainments, the Bow Horse Riding archery that the Manchu Qing attaches importance to, he is still very good at it.
In this way, it was a little stronger than his eleventh brother, that is, Yong Yao, who had also been considered by Qianlong at that time, but it was precisely because he was too partial, the literati were too heavy, and he was very disgusted with riding and shooting, which made the Qianlong Emperor very unhappy, after all, the Manchu Qing was the world on horseback, and the level of riding and shooting was low, and naturally he would be eliminated.
On the other hand, Jiaqing's comprehensive ability, although somewhat mediocre, was very balanced, which made the Qianlong Emperor finally choose him.
In addition, Jiaqing also had two points that made Qianlong quite satisfied, one was that he was the least negative among the many princes, and at that time, the ministers of the DPRK and the Central Committee praised him a lot.
"Only the fifteen kings (referring to Jiaqing) studied hard, had a strong and commanding attitude, grew up in forbidden, and had an excellent reputation." --- the evaluation of Jiaqing by the Minister of Korea and the Central Government
Second, Jiaqing's personality is very good, in Qianlong's words, it is very "dignified", compassionate, and self-control, perseverance and perseverance are good, this character is Qianlong's most satisfied.
Therefore, after several years of observation, Qianlong found that Jiaqing was a child who satisfied him in all aspects among the princes, so he would set Jiaqing as his successor.
Finally, there is a more important point, that is, Jiaqing is very obedient, which can be seen in the three years after Qianlong's Zen reign.
In 1796, the Qianlong Emperor officially ascended the throne and Jiaqing ascended the throne, but the government at this time was still controlled by Qianlong, after all, no emperor in ancient times was willing to take the initiative to surrender power, and the Qianlong Zen throne was also a helpless move that did not exceed the length of his grandfather Kangxi's reign, but the power after the Zen throne was still in his hands.
At this time, Jiaqing, in getting along with his father Qianlong, seemed extremely smart.
After Jiaqing ascended the throne, one of the biggest purposes of his actions was that he could not make any decisions, read the recitals, participate in various sacrifices, and there was no problem in receiving ministers from various countries, but he just did not issue any orders or make any decisions.
In the final decision-making power of everything, he will follow a principle, that is, "listen to the emperor (referring to Qianlong)'s punishment."
At that time, after seeing Qianlong, a Korean envoy once told in his memoirs that when the Jiaqing Emperor was in the upper court or attending a public occasion, as long as Qianlong was present, his eyes stayed on Qianlong, and Qianlong laughed and laughed, and once Qianlong had any action, he would also respond at the first time, appearing "extremely respectful."
"Serving the emperor, the emperor is also happy, laughing is also laughing, his eyes do not turn, only see the emperor's movements" --- "Records of the Joseon Lee Dynasty"
Jiaqing's behavior is not only described as "sensible", which makes Qianlong even more satisfied, and he is deeply happy that he did not choose the wrong successor.
Therefore, Jiaqing's ability to become Qianlong's successor is expected, reasonable, and inevitable.
In short, Qianlong chose Jiaqing for many reasons and considerations, the first is that Jiaqing is diligent and studious, not only has deep literary attainments, and riding and shooting is also good, the second is that Jiaqing's negative evaluation is less, and the personality also makes Qianlong satisfied; the third is that Jiaqing understands things and knows what not to do, and finally, and most importantly, at that time, because most of Qianlong's sons have died or died of illness, the range of choices can be limited, in other words, there is no choice, therefore, Qianlong will "pick the general among the lame". I chose Jiaqing, which can still be seen.