Dannenberg is a town on the River Jeetze, somewhat above its confluence with the Elbe, ESE of Lüneburg, and in the easternmost part of Niedersachsen.
It became part of Brunswick-Lüneburg in 1303. In 1569 the district around it as well as two other small enclaves became a Duchy for Henry, the elder brother of Duke William of Brunswick-Celle, who had taken the greater part of the lands. Henry’s second son became Duke of Brunswick-Wolfenbüttel in 1635 and succeeded his elder brother in Dannenberg the following year. In 1671 Dannenberg was transferred to Brunswick-Celle.