The death of Władysław IV on May 20 and the discordant interregnum had made the matters worse. Chancellor Jerzy Ossoliński and Voivode Adam Kisiel, a magnate influential with the Ukrainian population, advocated making the concessions necessary to placate the Cossacks. Other magnates, especially Wiśniowiecki, Aleksander Koniecpolski and Janusz Radziwiłł, demanded taking whatever radical punitive steps were required to quench the disorder. The convocation sejm was likewise indecisive and the newly appointed military chiefs incompetent, which resulted in a disastrous defeat at the Battle of Pyliavtsi in September. This allowed Khmelnytsky to move toward Lwów and Zamość, while the uprising expanded into Volhynia and Belarus.