Principality of Calenberg
When Duke Frederick Ulrich died childless in 1634 the Wolfenbüttel line of the Middle House of Brunswick ended with him. In 1635 Duke Augustus the Elder from the Middle House of Lüneburg received the Principality of Calenberg-Göttingen. After his death in 1636 his younger brother George became its ruler. He was successful as a general on the Swedish side and he also succeeded in 1637 in recovering the country and especially the towns for the Welfs. He initially ruled out of occupied Hildesheim, but then moved his residence to Hanover, which he also had built as a fortress. After his death in 1641 a separate peace was hastily concluded with the emperor, which had to be paid for by the return of the land acquired during the Hildesheim Diocesan Feud. George's sons, Christian Louis, George William, John Frederick and Ernest Augustus then ruled the Principality of Calenberg-Göttingen in succession.