Treaty of Pozvol

[1] The treaty was preceded by disputes between the members of the Livonian Confederation and military pressure by Sigismund II Augustus, King of Poland and Grand Duke of Lithuania, and provoked Russian tsar Ivan IV "the Terrible" to start the Livonian War.

[5] 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.

[1] Tsar Ivan IV "the Terrible", who in March had ended the Russo-Swedish War with the Treaty of Novgorod and since focussed on Livonia, claiming the subordination of Dorpat (Tartu) for a start.

[5] The tsar reacted to Pozvol by invading Livonia before the alliance would result in an actual mobilization of forces, starting the Livonian War (1558–1583).

[1] As a result, Reval (Tallinn) turned to Sweden for protection, Ösel (Saaremaa) was occupied by Denmark-Norway, and the order's grand master Gotthard von Kettler secularized what was left of the Russian-occupied order state, formally subordinated it to Sigismund II Augustus, and established himself as duke of Courland.