Calenberg was ruled by the House of Hanover (from the Principality of Lüneburg) from 1635 onwards; the princes received the ninth electoral dignity of the Holy Roman Empire in 1692.

Their territory became the nucleus of the Electorate of Hanover, ruled in personal union with the Kingdom of Great Britain from 1714 onwards.

When Eric I, Duke of Brunswick-Lüneburg chose the Principality of Calenberg as his part of the inheritance in 1495, he described it as "the land between the River Leine and the Deister".

However, in 1235, Henry's grandson, Otto the Child, was promoted to the rank of prince as a result of the reconciliation between the Houses of Hohenstaufen and Welf and was given the allodial estates of the family claimed by them in the area between Lüneburg and Brunswick as the new and independent Duchy of Brunswick-Lüneburg.

[1] While Henry retained the Wolfenbüttel lands, William was compensated with the newly created Principality of Calenberg.

It consisted of the rights formerly owned by the Principality of Lüneburg between the Deister range and the Leine river, as well as the former County of Wölpe, the lordship of Hallermund near Springe and the Homburg and Everstein dominions.

As the Welf princes all carried the ducal title and the territories they ruled were principalities within the Duchy of Brunswick-Lüneburg, their dominions were named after the main castle or town.

The reasons for his removal are debated; perhaps by his participation in many armed conflicts, Frederick was seen to pose a threat to Welf rule in Calenberg and Göttingen.

So William succeeded - albeit only briefly - in re-uniting the entire territory of the principalities of Calenberg, Brunswick-Göttingen and Brunswick-Wolfenbüttel.

Diplomatically, however, he was able to win a ruling from the Emperor Charles V that saw a large part of the Prince-Bishopric of Hildesheim added to his domain.

His second wife, Elisabeth of Brandenburg, however, whom he married in 1525, switched over to the new doctrine in 1535 and promoted it at the court, which then resided at Münden.

From 1574 he had Neustadt am Rübenberge developed as a fortified town and built Landestrost Castle within its walls as a Renaissance chateau, integrated into a bastion fortress based on the Italian model.

When Duke Frederick Ulrich died childless in 1634 the Wolfenbüttel line of the Middle House of Brunswick ended with him.

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 youngest son, Ernest Augustus, who ruled from 1679, carried on the successful policies of his father and his brothers.

Ernest Augustus switched to the side of the emperor and introduced primogeniture, contrary to the direction of his father.

By the reign of George of Calenberg in 1636, the principality had experienced 140 years of almost continuously poor government that cared little about the state.

In the Middle Ages and the Renaissance the cultural centres lay outside Calenberg in the towns of Brunswick, Hildesheim and Lüneburg.