Pugachev's Rebellion (or the Cossack Rebellion) of 1773-75 was the principal revolt in a series of popular rebellions that took place in Russia after Catherine II seized power in 1762. It began as an organized insurrection of Yaik Cossacks headed by Yemelyan Pugachev, a disaffected ex-lieutenant of the Russian Imperial army, against a background of profound peasant unrest and war with the Ottoman Empire. After the initial success, Pugachev assumed leadership of an alternative government in the name of the assassinated Tsar Peter III and proclaimed an end to serfdom. This organized leadership presented a challenge to the imperial administration of Catherine II.
The rebellion managed to consolidate support from various groups including the peasants, the Cossacks, and Old Believers priesthood. At one point, its administration claimed control over most of the territory between the Volga River and the Urals. One of the most significant events of the insurrection was the Battle of Kazan in July 1774.
Government forces failed to respond effectively to the insurrection at first, partly due to logistical difficulties and a failure to appreciate its scale, but the revolt was crushed towards the end of 1774 by General Michelsohn at Tsaritsyn. Pugachev was captured soon after and executed in Moscow in January 1775. Further reprisals against rebel areas were carried out by General Peter Panin.
The events have generated many stories in legend and literature, most notably Pushkin's historical novel The Captain's Daughter (1836). It was the largest peasant revolt in Russia's history.