served as abbot at Fulda from 822 to 842. Fulda Abbey owned such works as the Res Gestae by the fourth-century Roman historian Ammianus Marcellinus and the Codex Fuldensis, as well as works by Cicero, Servius, Bede and Sulpicius Severus. Counter-Reformation Prince-abbot Balthasar von Dernbach adopted a policy of counter-reformation. In 1571 he called in the Jesuits to found a school and college. He insisted the members of the chapter should return to a monastic form of life. Whereas his predecessors had tolerated Protestantism, resulting in most of the citizenry of Fulda and a large portion of the principality's countryside professing Lutheranism, Balthasar ordered his subjects either to return to the Catholic faith or leave his territories. He also ordered the Fulda witch trials, in which hundreds of people, including a number of crypto-protestants were arrested on charges of witchcraft alongside others. 18th and 19th centuries The foundation of the abbey of Fulda and its territory originated with an Imperial grant, and the sovereign principality therefore was subject only to the German emperor. Fulda became a bishopric in 1752 and the prince-abbots were given the additional title of prince-bishop. The prince-abbots (and later prince-bishops) ruled Fulda and the surrounding region until the bishopric was forcibly dissolved by Napoleon I in 1802. The city went through a baroque building campaign in the 18th century, resulting in the current "Baroque City" status. This included a remodeling of Fulda Cathedral (1704–12) and of the Stadtschloss (Fulda Castle-Palace, 1707–12) by Johann Dientzenhofer. The city parish church, St. Blasius, was built between 1771 and 1785. In 1764 a porcelain factory was started in Fulda under Prince-Bishop, Prince-Abbot Heinrich von Bibra, but shortly after his death it was closed down in 1789 by his successor, Prince-Bishop, Prince-Abbot Adalbert von Harstall. The city was given to Prince William Frederick of Orange-Nassau (the later King William I of the Netherlands) in 1803 (as part of the short-lived Principality of Nassau-Orange-Fulda), was annexed to the Grand Duchy of Berg in 1806, and in 1809 to the Principality of Frankfurt. After the Congress of Vienna of 1814–15, most of the territory went to the Electorate of Hesse, which Prussia annexed in 1866. 20th century From 1938 to 1943, Fulda was the location of a Nazi forced labour camp for Romani people. Fulda lends its name to the Fulda Gap, a traditional east–west invasion route used by Napoleon I and others.