when it was annexed by the Archbishopric of Trier Isenburg-Grenzau, 1258–1287, when it was divided into: Isenburg-Grenzau, 1287–1290, when it passed to Isenburg-Cleberg. Isenburg-Arnfels, 1286–1379, when it passed to Isenburg-Wied. Isenburg-Cleberg, 1287–1340, when it was divided into: Isenburg-Grenzau, 1340–1439, when it passed to Nassau-Beilstein. It subsequently passed to the Archbishopric of Trier in 1446, and was finally purchased by the Counts of Nieder-Isenburg in 1460. Isenburg-Büdingen, 1340–1511, when it was divided into: Isenberg-Büdingen-Ronneburg, or Isenburg-Ronneburg, 1511–1601, when it was annexed by Isenburg-Büdingen-Birstein Isenburg-Büdingen-Birstein (or Isenburg-Birstein), 1511–1628, which was divided into: Isenburg-Birstein, 1628–1664, when it passed to Isenburg-Offenbach Isenburg-Büdingen, 1628–1685, when it was divided into: Isenburg-Büdingen, 1685–1806, when it was mediatized to the Principality of Isenburg Isenburg-Wächtersbach, 1685–1806, when it was mediatized to the Principality of Isenburg Isenburg-Meerholz, 1685–1806, when it was mediatized to the Principality of Isenburg Isenburg-Marienborn, 1685–1725 Isenburg-Offenbach, 1628–1711, when it was divided into: Isenburg-Birstein, 1711–1744, when it became the Principality of Isenburg-Birstein. The Principality existed from 1744-1806, when it was renamed the Principality of Isenburg, 1806–1814/5 Isenburg-Eisenberg, 1711–1758, when it was absorbed back into the Principality of Isenburg-Birstein Isenburg-Philippseich, 1711–1806, when it was mediatized to the Principality of Isenburg Principality of Isenburg It was not until 1806 that there was a state called simply "Isenburg". When the Holy Roman Empire was defeated by Napoleon I of France in that year, the empire was abolished and the Confederation of the Rhine was established amongst the various German states. As an incentive to join the Confederation, it was stated that any state which joined could mediatise their neighbours. Prince Charles of Isenburg-Birstein joined the Confederation and was granted the mediatized Isenburgian Countships of Isenburg-Büdingen, Isenburg-Meerholz, Isenburg-Philippseich, and Isenburg-Wächtersbach. His Principality was renamed to Isenburg. The Principality continued under the rule of Prince Charles through the Napoleonic era, but was mediatised by Austria in December 1813, at the insistence of King Frederick William III of Prussia, who was angered that Isenburg had raised a regiment for French service by recruiting Prussian deserters and vagabonds. Isenburg was one of only three original member princes of the Empire to be mediatized at the end of the Napoleonic era (the others being Leyen and prince-primate Dalberg, Prince of Aschaffenburg). This decision was confirmed at the Congress of Vienna. The lands of the principality were divided between the Grand Duchy of Hesse-Darmstadt and the Electorate of Hesse-Kassel (or Hesse-Cassel). Rulers House of Isenburg Partitions