4. The Taiping Rebellion, the largest Chinese conflict since the Qing Conquest, is estimated to have been responsible for the deaths of between 20,000,000 and 70,000,000 people
The Taiping Rebellion was a Chinese civil war that raged from 1850 to 1864, fought between the Qing dynasty and the Taiping Heavenly Kingdom. Based in present-day Nanjing, the Taiping, led by Hong Xiuquan, was a fanatical Christian movement seeking to impose radical social change upon China. Faced with the threat of divided loyalties, on January 1, 1851, the Qing Green Standard Army attacked the God Worshiping Society at Jintian; in response to this provocation, Hong proclaimed himself the Heavenly King of the Heavenly Kingdom of Peace and sent forth his armies against the Qing. Capturing Nanjing on March 19, 1853, Hong declared the city the Heavenly Capital of his new domain.
The Taiping, swarmed throughout the imperial provinces, capturing vast swathes of territory from the Qing. With the Imperial Armies ineffective, the Xian Army, a militia force under Zeng Guofan, served as the primary defense against the dominant Taiping. Following an attempted coup within the Heavenly Empire in 1856, the Xian Army seized the opportunity to reclaim large portions of conquered land. Gaining momentum, the Xian besieged Nanjing in May 1862; despite efforts to break the siege by the superior Taiping numbers, the Qing loyalists held firm. On June 1, 1864, Hong died and Nanjing fell in his absence on July 19. Without central leadership the Heavenly Kingdom fractured, allowing for the gradual defeat of disunited rebellious factions across the next seven years.