The correct answer is - Taiping Rebellion.
From 1850 to 1864, China was in a terrible situation. There was a rebellion, or rather a full civil war on all of its territory. The reason for the rebellion was that the Chinese people were not able to stand the Manchu leadership anymore, or rather the Qing Dynasty, because of their irresponsibility and corruption. The Taiping Rebellion was led by the Taiping Heavily Kingdom with Hong Xiuquan as its leader. While there lot of initial victories and gained territories, the end result was actually a defeat.
