Yemelyan Pugachev, who led a major insurrection against the rule of Catherine II, was a Don Cossack, and was required to serve in the Russian army. He served in the Seven Years War and first Russo-Turkish War, but deserted during a leave of absence. He thereafter led an itinerant life, and came to formulate thoughts of rebellion against the depredations of Tsarist rule. In 1773, he proclaimed himself Tsar Peter III, who had been assassinated on Catherine's orders in 1762, exploiting a widely held peasant belief that Peter had not actually been killed. He organised revolt among the Yaitsk Cossacks, already divided into 'loyalist' and 'rebellious' factions and disturbed by a plan to organise them into Cossack regiments.
In September 1773, with a group of 300 Cossacks, he attempted to take Yaitskiy Gorodok, but was unable to secure the bridge across the River Chagan, and moved off in favour of an attack on Orenburg. The insurrection grew, Pugachev winning further recruits with his promises of liberty, land and provisions, and with threats of punishment to those who refused to support him. His supporters included many Tatars and Bashkirs as well as Cossacks, and his forces came to number more than 10,000, their organisation mimicking the Tsarist one in some respects. A detachment of Pugachev's forces moved into Yaitskiy Gorodok in December 1773, and Pugachev himself came to the town in January 1774, at one stage taking over the siege of the town's fortress, which was holding out obstinately. Its defenders included the father of the future celebrated Russian fable writer Ivan Krylov. Pugachev found time to marry a local girl, a Cossack named Ustinya Kuznetzova, although he had already married Sofia Nedyuzheva back in 1758. In April 1774, Tsarist forces under General Mansurov entered Yaitskiy Gorodok, coming to the rescue of the beleaguered fortress. Pro-Tsarist Cossacks rounded up local supporters of Pugachev, including the unfortunate Ustinya, and brought them to the fortress.
Elsewhere, Pugachev's rebellion had grown rapidly, helped by Catherine's initial failure to take the threat sufficiently seriously, and at its peak embraced much of the region between the Volga and the Urals, including the city of Kazan. But the comprehensive defeat of Pugachev's forces in August 1774 at Tsaritsyn, near Volgograd, proved a turning point, and when Pugachev made his way back to the Yaitsk Cossack region he was betrayed by a group of Cossacks and handed over to the authorities on 14 September 1774. Pugachev was placed in a small metal cage and sent to Moscow where, on 10 January 1775, in front of a large crowd, he was beheaded and quartered.
The Pugachev Rebellion seems to have encouraged Catherine towards greater conservatism. Her response was to introduce measures increasing central government control over the full territory of the empire and entrenching serfdom even more firmly.