 Though the Polish army was not defeated, its inability to defeat the rebellious Cossacks meant that the latter gained an upper hand in the negotiations; Ukrainian historiography calls the battle at Pereiaslav a victory, but this is disputed by Polish historiography.Fedorovych's military successes forced Koniecpolski to start negotiations with the Cossack leadership, which resulted in the 1630 Treaty of Pereiaslav.Many of the demands of the non-registered Cossacks and Fedorovych, their leader, were discarded in the treaty negotiations by other Cossack leaders.