The Three Kingdoms period began with the Han dynasty of Cao Pi and ended until the fall of Sun and Wu, and the unification of the Western Jin Dynasty officially ended, which can be roughly divided into three stages: the period of internal friction of the alliance (219-226), the period of joint counteroffensive (226-234), and the period of overall downturn (234-280).

【Period of internal friction in the alliance】

The beginning of the internal friction of the alliance can be traced back to the Battle of Xiangfan in the twenty-fourth year of Jian'an (219), Sun Quan sent Lü Meng and others to attack Guan Yu and seize Jingzhou, until the death of Cao Pi in the seventh year of the Huang Dynasty of Wei (226), and Sun Wu and Shu Han turned to defense.

During this period, because of the infighting between Shu Han and Sun Wu, the relationship between Sun and Liu alliance broke down, and Cao Wei was able to sit on the mountain and watch the fire and reap the benefits of the fisherman. After the battle of Yiling, the two sides reconciled, but the loss of Shu Han's national strength was serious, Zhuge Liang took power after the first pragmatic restoration of national strength and pacified the rebellion in the south, so Cao Wei was powerless to threaten, at this time Cao Pi had no external threat, three times to the south to crusade against Sun Wu, it can be said that Sun Quan was suppressed very badly, until Cao Pi died, Sun Quan was basically in a state of beating.

So in this period, it was the era when Cao Wei's family was dominant, Shu Han and Sun Wu had not yet been able to get out of the shadow of the early infighting, Shu Han was still recovering his national strength, and Sun Wu could only carry it himself.

[The period of joint counteroffensive]

In the seventh year of Wei Huang (226), Sun Quan immediately sent troops to the Northern Expedition after learning of Cao Rui's death, and Zhuge Liang also tried to make a move in Hanzhong shortly after quelling the rebellion in Nanzhong, and the Sun-Liu Alliance opened the curtain of the counteroffensive. Their counteroffensive did not end until the death of Zhuge Liang in the second year of Wei Qinglong (234).

In history, Sun Quan and Zhuge Liang carried out about six Northern Expeditions in this period, the scale of the Northern Expedition is large, the number of times, in ancient Chinese history is also relatively rare, among which Sun Wu in the early stage of Cao Wei's threat is relatively large, the Battle of Shiting Cao Xiu's fiasco is a clear example, but in the later period Zhuge Liang became stronger and stronger, the pressure on the Western Front became greater, and the last two Northern Expeditions have suppressed Sima Yi, especially the last time, Sima Yi has a local geography, military advantage, Even when Zhuge Liang was half a soldier and half a farmer, he still did not dare to confront the Shu Han army head-on, which shows the great threat of Zhuge Liang.

After Zhuge Liang's death, Shu Han's offensive basically came to an end, and the threat to Cao Wei was greatly reduced.

The main theme of this period is still a strong showdown, whether it is Cao Wei, Shu Han or Sun Wu, the performance is generally quite outstanding.

【Overall downturn】

Probably after the death of Zhuge Liang in the second year of Wei Qinglong (234), the Three Kingdoms era entered a long period of downturn, until the first year of Taikang (280) Jin Sima Yan destroyed Wu, whether it was Cao Wei, Sun Wu or Shu Han, they were not very strong, but everyone was comparing them at that time, what is the situation? It doesn't matter if I'm bad or bad, you're also bad, even worse than me.

First of all, Cao Wei, Emperor Cao Rui of Wei Ming, after the offensive of Sun Wu and Shu Han weakened, he also began to covet pleasure, build a large number of buildings, and collect the harem, Cao Wei's momentum has begun to weaken; After Cao Rui's death, he assisted the young Cao Fang with the Taiwei Sima Yi and the general Cao Shuang, and in the next ten years (239-249) Cao Wei's power was actually controlled by the general Cao Shuang, who was not a qualified leader or a suitable ruler.

After Sima Yi came to power, Cao Wei's internal contradictions began to intensify, after all, Sima Yi is not the Cao family, nor is it the legitimate successor of Cao Wei, and the power of the Sima family is not recognized by those ministers who are loyal to Cao Wei, and the result is that Wei has been in a state of internal instability for a long time, and the impact is extremely far-reaching, until Sima Yi's grandson Sima Yan changed the dynasty, and it took considerable time and energy to stabilize the situation.

When Sima Yi was in power, there was Wang Ling's rebellion, and his eldest son Sima Shi inherited his throne after the rebellion of Biqiu Jian, and in the Sima Zhao period, there was not only the Zhuge rebellion, but also the manna coup led by Cao Chao, and the Sima family was not once or twice purged within the imperial court, it can be said that although the Sima family occupied the Wei State in the later period, it was the strongest in China among the Three Kingdoms, but it was also very unstable internally due to the influence of the Sima family's seizure of power.

followed by Sun Wu, Sun Quan began to be a little dizzy in the middle and late stages of power, especially in the later period after the death of the eldest Sun Deng, Sun Quan not only set up the third son and grandson as the crown prince, but also took the fourth son and grandson as the king of Lu, which directly triggered the dispute between the two palaces, Sun Wu and the ministers, which led to the division of the country into two factions, the princeling party and the Lu Wang party, and the deep rift within the royal Sun family was also buried, and finally there were many powerful ministers implicated in death, including Lu Xun and Zhu Ju, two prime ministers!

After Sun Quan's death, the internal contradictions of Sun and Wu not only did not ease, but also further intensified, first Zhuge Ke just restored his own use and led to the tragic failure of the Northern Expedition, so he was killed by Sun Jun's coup d'état, and the original prince Sun He was later implicated and killed; Later, Sun Xiu was good at killing important ministers and abolishing the king, until Sun Xiu succeeded to the throne and removed Sun Qi, Sun Wu was stable for a few years, but the first few years of Sun Xiu's reign was actually Sun Wu's last good time, before Sun Xiu's death, Sun Wu had internal and external troubles, Jiaozhi was in turmoil, and his ally Shu Han was destroyed; After the new emperor Sun Hao came to power, Sun Wu was even more confused by this tyrant and faint monarch, the courtiers were treated like toys, the clan fled one after another, and Sun Wu was finally destroyed by his hands.

Compared with Wei and Wu, although Shu Han was the weakest, its political situation was also the most stable. After the death of Zhuge Liang, there was basically no coup d'état and large-scale rebellion in Shu Han, which was much better than Wei Wu, and those core ministers of Shu Han did not hear of anyone who was killed because of their participation in the coup and rebellion, although Liu Chan was faint in his later years, but at least he did not kill people indiscriminately, and the number of ministers who died in the other two countries is not to be discussed, there are too many deaths.

The biggest and most famous internal struggle in Shu Han was basically the time when Zhuge Liang got rid of Li Yan, but Li Yan did not die at that time, but just stepped down. Because although Li Yan was born in Jingzhou, he had already taken refuge with Liu Zhang after the Battle of Chibi, and he was not an old courtier brought by Liu Bei from Jingzhou, he belonged to half of the Jingzhou faction, and he was also half of Dongzhou, but because of this, he did not have a deep relationship with both sides, especially within the Dongzhou faction, Li Yan took refuge in Liu Zhang too late, and his influence on the Dongzhou faction was even more limited. Li Yan's relationship with his colleagues, fellow villagers and subordinates is not very good, which can be seen from relevant examples, so Li Yan's position in Shu Han is actually very embarrassing.

Although Shu Han is the most stable internally, but because the foundation is too weak, so it can not withstand civil strife and consumption, after the death of Jiang Wan and Fei Yi, the overall situation of Shu Han has been uncontrolled, although Chen Ji did not have a clear record of directly disturbing the government, but he connived at Jiang Wei's large-scale Northern Expedition, and connived at the eunuch Huang Hao to participate in the government, which led to the direct destruction of Shu Han in the hands of the two in the future.

In fact, in history, the Cao family, the Sun family, the Sima family and other royal princes have records of slaughtering the city, and only the Liu family has basically no record of this, from Liu Bei to Liu Chan, and even Liu Yu and others have not seen this record, at least I have not noticed it personally. Of course, this is just a digression in this chapter.