Principality of Grubenhagen
|Principality of Grubenhagen
|State of the Holy Roman Empire|
Coat of arms
Herzberg from 1486
|Historical era||Middle Ages|
|-||Henry I the Admirable
Duke of Brunswick
Prince of Grubenhagen
Lower Saxon Circle
|-||Line extinct, annexed
|-||Ceded to Principality of Lüneburg||1617|
The Principality of Grubenhagen was a subdivision of the Welf Duchy of Brunswick-Lüneburg in the Holy Roman Empire. It is also known as Brunswick-Grubenhagen. Grubenhagen was located around the southwestern edge of the Harz, and included the towns of Osterode am Harz, Herzberg am Harz, Duderstadt, Einbeck and the eastern exclave of Elbingerode.
Grubenhagen was split off from the Brunswick subdivision of the duchy in 1291; its first ruler was Henry I, Duke of Brunswick-Lüneburg. Henry's sons split the small principality further in 1322 as they themselves had numerous heirs; Prince Otto of Grubenhagen, son of Duke Henry II, in view of his small share left for Montferrat, married Queen Joan I of Naples in 1376 and became Prince of Taranto in 1383. The Principality of Grubenhagen was finally reunited in 1526 under the rule of Duke Philip I of Brunswick-Lüneburg.
When in 1596 the Grubenhagen branch became extinct, the territory was disputed by the different lines of the Brunswick-Lüneburg dynasty. Duke Henry Julius of Brunswick-Wolfenbüttel occupied Grubenhagen, his son Frederick Ulrich however had to cede it to Prince Christian of Lüneburg by a 1617 ruling of the Imperial Chamber Court (Reichskammergericht) at Speyer. With the Principality of Lüneburg, Grubenhagen was finally inherited by Prince Christian Louis of Calenberg in 1648. After his death in 1665 Grubenhagen ceased to exist as an independent principality. Formally, it remained a state of the Holy Roman Empire until its dissolution in 1806.
A Calenberg-Grubenhagen Landschaft (administrative division) still exists today.
Dukes of Brunswick-Lüneburg, Princes of Grubenhagen 
- Henry I the Admirable 1291-1322
- Henry II, son 1322-1351, jointly with his brothers
- Albert I, son of Ernest I 1361-1383, jointly with his brother John II
- John II 1361-1364
- Eric, son of Albert I 1383-1427
- Henry III, son of Eric 1427-1464, jointly with his brothers Albert II and Ernest II
- Albert II 1427-1485
Principality divided in 1479.
Grubenhagen re-united in 1526.