The Third Battle of Nanking is the last major engagement of the Taiping Rebellion, occurring in 1864 after the death of the king of the Taiping Heavenly Kingdom, Hong Xiuquan.
There are probably more than a million troops in the battle and the Taiping army sustains 100,000 dead (and many more wounded) in the three day clash.
Following the defeat of the Taiping army the Imperial troops, commanded by Zeng Guofan, slaughter much of the city's population.
Nanking had been the capital of the Heavenly Kingdom and is known by the Taipings as Tianjing (Heavenly Capital - the name should not be confused with Tianjin, China's third largest city).
This battle is the effective end of the Taiping army and the last major Taiping city to return to Imperial control.