Albert I of Brandenburg, also called The Bear (Ger: Albrecht der Bär), becomes the founder of the Margraviate of Brandenburg, Germany and the first margrave.

Albert the Bear was the first margrave of Brandenburg from 1157 to his death and was briefly duke of Saxony between 1138 and 1142.

Margrave was originally the medieval title for the military commander assigned to maintain the defence of one of the border provinces of the Holy Roman Empire or a kingdom. That position became hereditary in certain feudal families in the Empire and the title came to be borne by rulers of some Imperial principalities until the abolition of the Empire in 1806. Thereafter, those domains were absorbed into larger realms or the titleholders adopted titles indicative of full sovereignty.

Brandenburg, officially the State of Brandenburg, is a state in northeastern Germany. Brandenburg borders Poland and the states of Berlin, Mecklenburg-Vorpommern, Lower Saxony, Saxony-Anhalt, and Saxony. It is the fifth-largest German state by area and the tenth-most populous, with 2.5 million residents. Potsdam is the state capital and largest city. Other major towns are Cottbus, Brandenburg an der Havel and Frankfurt (Oder).