Duchy of Livonia

The Duchy of Livonia, also referred to as Polish Livonia or Livonia, was a semi-autonomous vassal state of the Grand Duchy of Lithuania and, from 1569, the Polish–Lithuanian Commonwealth. Established in 1561 following the dissolution of the Livonian Confederation during the Livonian War, it comprised most of present-day northern Latvia and southern Estonia. The duchy existed until 1629, when most of its territory passed to the Swedish Empire after the Polish–Swedish War (1600–1629).

The duchy was created under the terms of the Treaty of Vilnius (1561), by which the Livonian nobility accepted the suzerainty of the Grand Duke of Lithuania in return for guarantees of their traditional privileges. Although subject to the Commonwealth's monarch, Livonia retained its own provincial administration, legal institutions, and the dominant political influence of the Baltic German nobility. Lutheranism remained the principal confession despite the Catholic faith of the ruling dynasty.