Bohdan Khmelnytsky
Bohdan Khmelnytsky, leader of the Ukrainian Cossacks, learned about Radziwiłł's plans while besieging Zbarazh. He sent part of his forces, an army of about 10,000, under another Cossack leader, Mykhailo Krychevsky (Stanisław Krzeczowski), to support Podobajła against the Commonwealth.