Frederick August I, Duke of Oldenburg
Friedrich August, Duke of Holstein-Oldenburg (20 September 1711 in Gottorp, Schleswig – 6 July 1785 in Oldenburg) was the son of Christian August, regent of Holstein-Gottorp and his wife Margravine Albertine Friederike of Baden-Durlach. Marriage and issue. Frederick Augustus married on 21 November 1752 to Princess Ulrike Friederike Wilhelmine of Hesse-Kassel; the couple had three children: Titular History. Empress Catherine the Great of Russia, on behalf of her son Paul of Russia, last of the Dukes of Holstein-Gottorp, ceded the lands of that duchy to Denmark. In exchange, Denmark ceded  the Duchy of Oldenburg to the Prince Bishops of Lübeck, a cadet branch of the Dukes of Gottorp. Thus, Friederich August of Holstein-Gottorp, Prince Bishop of Lübeck, became Duke of Oldenburg. His son and heir apparent, Peter Friedrich Wilhelm, succeeded him as Wilhelm I, Duke of Oldenburg.