John I, Margrave of Brandenburg

Who was John I, Margrave of Brandenburg?

John I, Margrave of Brandenburg was from 1220 until his death Margrave of Brandenburg, jointly with his brother Otto III "the Pious".

The reign of these two Ascanian Margraves was characterized by an expansion of the Margraviate, which annexed the remaining parts of Teltow and Barnim, the Uckermark, the Lordship of Stargard, the Lubusz Land and parts of the Neumark east of the Oder. They consolidated the position of Brandenburg within the Holy Roman Empire, which was reflected in the fact that in 1256, Otto III was a candidate to be elected King of the Germans. They founded several cities and developed the twin cities of Cölln and Berlin. They expanded the Ascanian castle in nearby Spandau and made it their preferred residence.

Before their death, they divided the Margraviate in a Johannine and an Ottonian part. The Ascanians were traditionally buried in the Lehnin Abbey in the Ottonian part of the country. In 1258, they founded a Cistercian monastery named Mariensee, where members of the Johannine line could be buried. In 1266, they changed their mind and founded a second monastery, named Chorin, 8 km southwest of Mariensee.