Treaty of Vilnius (1561)
With the treaty, the non-Danish and non-Swedish part of Livonia, with the exception of the Free imperial city of Riga, subjected itself to the Grand Duke of Lithuania, Sigismund II Augustus with the Pacta subiectionis (Provisio ducalis).
In turn, Sigismund granted protection from the Tsardom of Russia and confirmed the Livonian estates' traditional privileges, laid out in the Privilegium Sigismundi Augusti.
[6] The order ceded about one seventh of its territory, allowed Sigismund to garrison its most important castles, and agreed to share with him any conquests made from Ivan IV.
[7] The alliance was intended to neutralize the imminent threat of annexation of the order's lands by Russia, yet despite earning military support from Polish-Lithuanian chancellor Mikołaj "the Black" Radziwiłł, Kettler was defeated in Ērģeme (Ermes, 1560) and unable to prevent the occupation of most of Livonia by Russian forces.
[6] After the treaty, the disintegrating order agreed to secularization if necessary, and since Sigismund was reluctant to support it militarily, continued its search for a protector at the courts of Denmark-Norway and the Holy Roman Emperor.
[6] In November 1561 the new Grand Master Gotthard Kettler secularized the Order and surrendered Livonia to Sigismund Augustus, retaining the Duchy of Courland for himself as Polish-Lithuanian vassal.
[8] In the Duchy of Courland and Semigallia, a stable political system was established on the basis of the 1561 treaty, and only in 1617 this was modified by the Formula regiminis and Statuta Curlandiæ, which granted the indigenous nobles additional rights at the duke's expense.
[5] After the Polish-Swedish victory in the Battle of Wenden (1578), Russian forces were subsequently expelled from Livonia, and the Livonian War ended with the treaties of Jam Zapolski and Narva-Plyussa.
[10] Báthory however regarded the re-conquered territories as his war booty,[10] refused to confirm the Privilegium Sigismundi Augusti, and in 1582 replaced it with the Constitutiones Livoniae, which tolerated Indigenat and Augsburg Confession, but revoked their status as elementary right and else did not contain any privileges.
[15] Under Stephen Báthory, the Duchy of Livonia was subjected to Counter-Reformation led by bishop Otto von Schenking, who had converted to Catholicism, and the Jesuits of Riga and Dorpat (Tartu).
[16] These measures however proved to have only limited impact on the Estonian and Latvian population, while alienating the German gentry to a degree that they supported the Swedish take-over of Livonia (without Latgalia, Courland and Semigallia), formalized in the treaties of Altmark (1629) and Stuhmsdorf (1635).
