Duchy of Brunswick-Lüneburg
Henry was the son of Henry the Mild, Duke of Brunswick-Lüneburg. On their father's death in 1416, Henry and his brother William inherited the Principality of Lüneburg, while under the guardianship of the City Council of Lüneburg (Lunenburg). When the Duchy of Brunswick-Lüneburg was reorganized in 1428, Henry and his brother swapped Lüneburg for the Principality of Brunswick, including Calenberg.