Lilienthal, Lower Saxony conversion of the Cistercian nuns, it became a Lutheran Women's Convent, and until the end of the Thirty Years' War in 1648 it remained in deplorable conditions. In 1650, the city went through secularization. The land once belonging to the convent, which had become fragmented, developed into the small town of Lilienthal. In 1648, according to the terms of the peace treaty that ended the Thirty Years' War (The Peace of Westphalia), the Prince-Archbishopric was transformed into the Duchy of Bremen, ruled together with the Principality of Verden, which were first ruled in personal union by the Swedish Crown. Queen
Peace of Münster for approval; it was ratified by the Spanish and Dutch delegations on 15 May, with the States General narrowly approving the Treaty on 5 June 1648. The Peace of Münster together with the Treaty of Münster between the Holy Roman Emperor, France and their allies and the Treaty of Osnabrück involving the Holy Roman Empire, Sweden and their allies were collectively known as the Peace of Westphalia. While European conflict continued, this marks a significant point in the transition to sovereignty based on states rather than individuals e.g. the Hapsburgs. Sovereignty has been defined by historian Harry Hinsley as "the