Essen
Essen was the territory of a secular abbey on the Ruhr. In 1337 Katharina von der Mark, daughter of Count Engelbert II of the Mark, was elected princess-abbess.
In 1357 Emperor Charles IV confirmed the abbey's rights. Its protectors passed to Cleves and, after 1609, Brandenburg. Prussian troops occupied the territory in 1802; the abbey was dissolved in 1803, and its lands returned to Prussia in 1813.