The Polish–Swedish War (1626–1629) was a conflict between the Kingdom of Poland and the Swedish Empire. It primarily arose from territorial disputes in the Baltic region, particularly over control of the Baltic Sea trade routes. The war saw several battles, with both sides seeking to expand their influence in northern Europe. The war concluded with the Treaty of Altmark in 1629, which favored Sweden, granting it significant territories in Livonia and parts of Prussia. This conflict was part of the larger struggle for dominance in the region, influencing future relations between Poland and Sweden.