In February 1651, Hetman Kalinowski advanced against the Cossacks, but suffered heavy losses and withdrew to Kamieniec Podolski; in May he fought his way to Sokal, where he joined the gathering of the Crown army. In June, both the regular army and "szlachta"'s pospolite ruszenie moved decisively against the Tatar-Cossack forces. At the Battle of Berestechko King John Casimir was able to impose on the enemy the site for the confrontation he chose and in heavy fighting destroy the Cossack army, while the fleeing Tatars took Khmelnytsky with them. However, a majority of the Cossack soldiers were saved by one of their outstanding commanders, Ivan Bohun.