What happened
On the Yangtze near modern Chibi, Hubei, the allies — with Sun Quan’s commander Zhou Yu prominent — used a fire attack against Cao Cao’s ships and forced his retreat north.
Background
Cao Cao had unified the north, and the Han court had fallen under his control. He moved south to complete the reunification of the empire.
Consequences
Reunification was blocked, and the empire settled into the three-way division formalized after 220 as Wei, Shu Han, and Wu. The battle became one of the most famous in Chinese history, retold in the Romance of the Three Kingdoms.