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Events on Sunday 18 January 1654 1
1654Pereyaslav AgreementCossack Hetmanate swears allegiance to the Tsar of RussiaHetman Bohdan Khmelnytsky and the Cossack leadership of the Zaporizhian Host swore loyalty to Tsar Alexis of Russia at Pereyaslav, seeking protection against Poland-Lithuania. The agreement brought much of Ukraine under Russian suzerainty and triggered a new war between Russia and the Commonwealth. Its interpretation remains disputed by Russian and Ukrainian historians.