Emperor Hui of Jin

As Jin Wudi began integrating the former Wu Kingdom into his Jin Empire, he made a fatal error that threatened to bring down the dynasty.

He scored an own goal by selecting as his heir his son and crown prince, Sima Zhong.

This young man was not at all Chinese emperor material.

Neither did he have the right stuff as far as being suitable for politics.

And Sima Yan, Jin Wudi, he did the Confucian thing rather than the right thing.

And this ends up leading to the brevity of the Jin dynasty in its western period.

On paper, Sima Zhong was the obvious choice.

He was the oldest surviving son of Emperor Wu.