Frederick IV, Landgrave of Thuringia

He was the son of Landgrave Balthasar of Thuringia and his first wife, the Hohenzollern princess Margaret of Nuremberg. His father had received the Landgraviate of Thuringia in the 1382 Division of Chemnitz and was able to largely extend his territories in several skirmishes with the local nobility. After the death of his first wife Margaret in 1391, he secondly married the Ascanian princess Anna of Saxe-Wittenberg.

Landgrave Balthasar planned to marry his son off to Elizabeth of Görlitz, a grand-daughter of the late Luxembourg emperor Charles IV; nevertheless, these attempts had already failed, when Frederick succeeded his father in 1406. One year later he married Countess Anna (d. 1431), the daughter of Count Günther XXX of Schwarzburg-Blankenburg. Their marriage remained childless.

Frederick is considered a relatively weak ruler, who was at times very dependent on the influence of his wife and her relatives. To finance his lavish court, he sold more and more land and titles. In 1436, he had all Jews expelled from Thuringia.

After Frederick's death without heirs, Thuringia was inherited by his two Wettin cousins, Elector Frederick II of Saxony and his brother William III. He had already sold them the more remote areas of Meissen some years earlier for 15000guilders. The succession led to the 1445 Division of Altenburg and the subsequent Saxon Fratricidal War.

• Heinrich Theodor Flathe (1877), "Friedrich (IV.), der Einfältige oder Friedfertige, Landgraf von Thüringen", Allgemeine Deutsche Biographie (ADB) (in German), 7, Leipzig: Duncker & Humblot, p. 567

• Entry in the Saxon Biography
• www.genealogie-mittelalter.de