What is the worst "disappearance" in history?

The most severe "disappearance" in history, I think Sima Jia took the position of an emperor directly during the Three Kingdoms period.

We all know that the story of Romance of the Three Kingdoms is about Wei Shuwu, and it is about Wei, Shu and Wu competing for the world. Cao Pi, the son of Cao Cao, was the first person to proclaim himself emperor. He forced Emperor Xian of Han to take his place and established the State of Wei. Later, Sun Quan and Liu Bei also proclaimed Wu Dong and Han Zhaolie respectively. Since then, the three countries of Wei Shuwu have been at war for years. There were many wars between Zhuge Liang's seven northern expeditions and Shu and Wu.

When the Three Kingdoms competed for hegemony, Cao Cao recruited a very effective adjutant-Sima Yi. Sima Yi is an outstanding strategist and strategist who helped Wei win many wars. Therefore, Cao Cao was full of vigilance against Sima Yi, fearing that he was too successful to succeed. Therefore, Cao Cao left a legacy before he died, and Sima Yi could not be exposed to the army, otherwise Wei would be in danger.

After Cao Cao's death, Cao Pi did not strictly carry out Cao Cao's wishes. Sure enough, after three generations of Sima Yi, Si Mazhao and Sima Yan, Sima Jia has established enough prestige in the army, the people and the court. Therefore, during the period of Sima Yan, he forced Wei Mingdi and Cao Huan to meditate with him, and formally established the Jin Dynasty, known as the Western Jin Dynasty in history.

But in fact, as early as the time, he was already preparing for the replacement of Wei, but he died before it was officially implemented, so there will be a saying that "everyone knows each other" in later generations.

After three generations, Sima Jiacheng replaced the self-made Wei State with Cao Cao and Cao Pi, which can be said to be the most serious omission.