Albert I was the eldest son of the Duke Ernest the elder of Grubenhagen and his wife, Adelheid of Eberstein.
On 28 Jun 1361, he shared a letter of tribute from the City of Brunswick with his brother John, but later that year, he got into a feud with Count Otto of Waldeck and his son Henry.
The territories of Landgrave Frederick III of Thuringia were particularly hard hit by the forays of Albert and his vassals.
The account of this attack contains the first mention of a gun in Brunswick (diz waz die erste buchse, dy yn dessin landin vernommen wart).
The Landgrave devastated towns and villages, and captured and tore down the robber castles of several of Albert's vassals and thereby forced him to sue for peace.