In the first five years after the onset of the Chinese Cultural Revolution, one of the largest political upheavals of the 20th century paralyzed a highly centralized party state, leading to a harsh regime of military control. Despite a wave of post-Mao revelations in the 1980s, knowledge about the nationwide impact of this insurgency and its suppression remains selective and impressionistic, based primarily on a handful of local accounts. Employing a dataset drawn from historical narratives published in 2,213 county and city annals (99 percent of local jurisdictions), this article charts the temporal and geographic spread of a mass insurgency, its evolution through time, and the repression through which militarized state structures were rebuilt. Comparisons of published figures with internal investigation reports, and statistical estimates from sample selection models, yield estimates that range from 1.1 to 1.6 million deaths and 22 to 30 million victims of various forms of political persecution. The vast majority of casualties were due to organized repression by authorities, not the actions of insurgents in the course of rebellion. Despite the large overall death toll, per capita death rates were considerably lower than a range of comparable cases, including the Soviet purges at the height of Stalinist terror in the late 1930s.