John III, Count of Holstein-Plön

Who was John III, Count of Holstein-Plön?

John III of Holstein-Plön, called John the Mild, was a Count of Schauenburg and Holstein-Plön and Holstein-Kiel, ruling Holstein-Plön and Holstein-Kiel. Together with Count Gerhard III of Holstein-Rendsburg John III was the lord ruling in guardianship the Danish Duchy of Schleswig 1332–1340. He was known as “John the Mild”.

He was the son of Count Gerhard II the Blind of Holstein-Plön and of the Danish Queen Dowager Agnes of Brandenburg, a fact that made him a half-brother of Eric VI and Christopher II. In 1312 John and his brother Gerhard IV succeeded their father as co-ruling counts of Holstein-Plön. In 1316 John III inherited Holstein-Kiel from his father's cousin John II the One-Eyed and thus left Holstein-Plön for his brother Gerhard IV as sole ruler. A wealthy man by inheritance John very early acted as a powerful local prince funding Danish warfare and co-operating with his cousin Gerhard III.

His financial support of the Danish kings quickly made him one of their leading creditors with his chief possession in Funen. During the rebellion against Christopher II 1326 John supported Gerhard III and the Danish magnates and enlarged his Danish possessions.