 Complete the following phrase:  Initially the captured Polish soldiers belonged to the Cossacks allies, the Crimean Tatars. After the battle, the Cossacks paid the Tatars for possession of the prisoners, and promptly slaughtered the Polish captives to avenge Khmelnystskys defeat at Berestechko in June 1651. According to Jasienica, it was the Cossack colonels Ivan Zolotaryenko and Ivan Vysochin who bought them from the Tatars. According to Widacka, Cossacks commander Khmelnystsky himself contributed 50,000 thalers for that purpose. According to Gruševskij, Pasicznyk, Duda and Sikora, the decision to execute the prisoners was made by Khmelnytsky himself. Afterward, between 3,000 and 5,000 elite Polish soldiers and officers, including 3,500 members of szlachta, were tied up and massacred in two days of methodical beheadings and disembowelments. Zolotaryenko supervised the executions yelling Revenge for Berestechko!, a reference to an earlier Cossack defeat at the hands of the Poles in the 