. This gave him extra cavalry, mainly under Togay Bey. The Poles tried, with occasional success, to split the alliance. Crimean horsemen accompanied Khmelnytsky on this 1648 campaign when he got almost as far as Lviv. Next year Islyam helped win the Battle of Zboriv (1649). The withdrawing Tatars were permitted to ravage the country they passed through. Some claim that Islyam was bribed by the Poles and that he ravaged mostly Cossack territory. In 1651 the Poles sent a large army and won the Battle of Beresteczko because the Tatars fled the field. Khmelnytsky went after them and was held hostage for a while by Islyam. In 1652, following the Battle of Batih, the Cossacks purchased the Polish prisoners from the Tatars and slaughtered them. Howorth says that in 1653 Islyam ravaged the country around Bar and Kaminetz and left after receiving a ransom.   Other sources have Islyam present at the Battle of Zhvanets at about the same time. In January 1654, by the Treaty of Pereyaslav, the Cossacks accepted Russian supremacy, thereby provoking the Russo-Polish War (1654–1667). Islyam died shortly after.