Isenburg

The lords of Isenburg, an old noble family of the Middle Rhine, took their name from the castle of Isenburg in the Westerwald, built around 1100 by the brothers Rembold and Gerlach. The house split in 1137 into the Isenburg and Limburg-Covern lines, and thereafter into many branches.

Around 1300 Ludwig of Isenburg married the heiress of Buedingen, and by 1376 his descendants had made good that inheritance; they became imperial counts in 1442. The Lower Isenburg lines died out, the Grenzau branch last in 1664, while the Buedingen line subdivided into several branches.

In 1744 the Birstein line was raised to princely rank, and in 1806 the Confederation of the Rhine united the Isenburg lands into a single Principality of Isenburg. The principality was mediatized after 1815 and divided between Hesse-Darmstadt and Hesse-Kassel in 1816.