War of the Eight Princes
Emperor Wu Di of Jin died, passing the throne onto his mentally disabled son, who was to be knownas Emperor Hui Di (r. 290-307). But the real sovereign was Hui Di's wife Jia, who ruled the empire ruthlessly for eight years. Not wanting to abdicate to Prince Sima Yu, a son whom the emperor had with another woman, Empress Jia worked out a plan to have him eliminated.
Empress Jia had a letter dictated in the manner of the prince, urging the emperor to abdicate. Then she invited the prince to dinner and got him very inebriated. Semi-conscious, Prince Sima Yu yielded to the empress' manipulations and copied out her letter.
The next day Empress Jia had her husband summon all the officials and showed them the letter that the prince had copied out, accusing him of treason. The officials did not believe Prince Sima Yu to be capable of this, but when the empress compared the handwriting, they could hardly speak up for the prince. The case established, Empress Jia deprived Sima Yu of the title of crown prince.
Public opinion among court officials, always against Empress Jia and her tyranny, was outraged at the deprivation of Sima Yu's title. Prince Sima Lun saw this as a good opportunity to gain power. Worried about Sima Yu beating him to the sovereignty, he started a rumor that court officials were plotting his restoration. The rumor worked; fearful of retribution, Empress Jia had Sima Yu poisoned. Then, using the crime of poisoning as the pretext, Sima Lun sent Sima Jiong to arrest Empress Jia.
Dismayed, the empress demanded why he was here with all these armed officers.
"In the name of His Majesty, you are under arrest," was the answer.
"But my own words are in the name of His Majesty," cried out the empress, "I cannot consider any other decree as valid or effective! "
However, her words could not save her this time. She was arrested and beheaded.
Once he became the virtual dictator of the empire, Prince Sima Lun's ambitions grew.
He went as far as placing the emperor under house arrest, and then ascended the throne himself. He rewarded each of his followers with a position in his government. When, given all the newly created positions, there was a shortage of marten tails, worn as a standard head ornament by the officials, the government improvised by using dog tails.
Princes outside the capital learnt of the usurpation and soon joined in a fight for the throne. Because eight princes were involved, the war is referred to as the "War of Eight Princes."