Taiping Rebellion
The Taiping Rebellion was a rebellion in 1850 led by Hong Xiuquan, who had received a Christian upbringing. Its goal was to overthrow the Chinese Qing Dynasty and replace it with a "Heavenly Kingdom of Great Peace". The rebellion enjoyed widespread initial success, causing massive destruction throughout much of southern and central China and capturing many major cities.
Although an appeal for an alliance with their fellow Christians was made to the British and French forces engaged against Chinese imperial forces at the same time in the Opium War, no serious thought was given to such an alliance by the Europeans.
Tens of millions of people are believed to have died as a consequence of the Taiping Rebellion, both as a result of fighting and the capture of cities, with no prisoners being taken by either side, and through the famines resulting from the devastation of the Chinese countryside.