Emperor Wu of Jin

Emperor Wu enfeoffed 27 of his sons as princes with military commands and territories, hoping to strengthen the imperial family. This policy backfired, as the princes later rebelled in the War of the Eight Princes, leading to the dynasty's collapse.

Sima Yan forced the abdication of Cao Huan, the last emperor of Cao Wei, and proclaimed himself Emperor Wu of Jin. He established the Western Jin dynasty with Luoyang as its capital. This ended the Cao Wei dynasty and began a new imperial line.

Emperor Wu of Jin launched a six-pronged invasion of Eastern Wu, the last of the Three Kingdoms. Wu's capital Jianye fell, and its emperor Sun Hao surrendered. This conquest unified China under the Western Jin dynasty, ending the Three Kingdoms period after 60 years.

After unifying China, Emperor Wu abolished the military agricultural colonies (tuntian) that had sustained the Three Kingdoms' armies. He demobilized many soldiers and returned them to civilian farming. This reduced military spending but weakened the dynasty's defensive capacity.

After unification, Emperor Wu indulged in luxury, building palaces and accumulating concubines. He neglected governance, leading to corruption and factionalism at court. This decadence contributed to the dynasty's instability and the later War of the Eight Princes.