Sigismund II Augustus
An ongoing Danish mediation of this conflict became void with the intervention of Sigismund II Augustus, king of Poland and Grand Duke of Lithuania and by the terms of Cracow protector of Wilhelm's brother, Albert. He demanded that Wilhelm and Christopher be released and the Livonian Confederation accept his protection. When he declared war and raised an army to underline his demands, which left for Livonia in July 1557, the Livonians gave in and signed three respective treaties on 14 September in the encampment of Sigismund II Augustus' army near Pozvol (Pasvalys, Podzwol, Pozwoł).