Cossack Hetmanate

Timeline

1. 1651Berestechko · Volyn OblastFrom June 28 to July 10, 1651, the Battle of Berestechko saw some 80,000 Polish-Lithuanian troops under John II Casimir face Khmelnytsky's roughly 100,000 Cossack and Crimean Tatar allies. The Crimean khan Islam III Giray suddenly withdrew, collapsing the Cossack line with heavy losses. In September the Treaty of Bila Tserkva forced the Hetmanate to cut registered Cossacks from 40,000 to 20,000 and drop demands for an Orthodox archbishop's seat in the council, foreshadowing later appeals for Russian protection.
2. 1654Pereyaslav · PereyaslavIn January 1654 Khmelnytsky convened a Great Rada at Pereyaslav and declared acceptance of the protection of Russian Tsar Alexis. The agreement confirmed Cossack internal autonomy: a registered quota of 60,000, the right to elect a hetman, independent diplomacy (with notice to the tsar), and traditional judicial institutions. Yet the two sides fundamentally disagreed on its nature—the Cossacks saw a military alliance, Russia a submission into its sovereign realm—and this interpretive rift ran through the Hetmanate's entire history.
3. 1657–1659Chyhyryn · Cherkasy OblastKhmelnytsky died in August 1657; his son Yuri briefly succeeded before being deposed, and the anti-Russian hetman Ivan Vyhovsky took power. In 1658 Vyhovsky signed the Hadiach Agreement with Poland, planning to admit the Hetmanate as a third equal member of the Polish-Lithuanian Commonwealth as the 'Principality of Rus'. That September a Cossack-Crimean force routed the Russians at Konotop. But the agreement lacked grassroots support, ordinary Cossacks turned to Russian protection, Vyhovsky resigned, Yuri Khmelnytsky was restored, and the Hetmanate again recognized Russian suzerainty (Second Pereyaslav Agreement, 1659).