Nanjing
Both the Qing viceroy and the Taiping king resided in buildings that would later be known as the Presidential Palace. When Qing forces led by Zeng Guofan retook the city in 1864, a massive slaughter occurred in the city with over 100,000 estimated to have committed suicide or fought to the death. Since the Taiping Rebellion began, Qing forces allowed no rebels speaking its dialect to surrender. This policy of mass murder of civilians occurred in Nanjing.

Q: When did Qing troops regain Nanjing?
1864