"Otto III, nicknamed the pious (1215 – 9 October 1267 in Brandenburg an der Havel) was Margrave of Brandenburg jointly with his elder brother John I until John died in 1266. Otto III then ruled alone, until his death, the following year.
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." - (en.wikipedia.org 06.04.2020)
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