The Electorate of Brunswick-Lüneburg (German: Kurfürstentum Braunschweig-Lüneburg) was an Electorate of the Holy Roman Empire, located in northwestern Germany. It was colloquially known as the Electorate of Hanover (German: Kurfürstentum Hannover or simply German: Kurhannover), after its capital city of Hanover. For most of its existence, the electorate was ruled in personal union with Great Britain.
The Prince-Elector of Hanover became King of Great Britain in 1714. As a consequence, a reluctant Britain was forced time and again to defend the King's German possessions. However, Hanover remained a separately ruled territory with its own governmental bodies, and the country had to sign a treaty with Great Britain whenever Hanoverian troops fought on the British side of a war. Merged into the Napoleonic Kingdom of Westphalia in 1807, it was re-established as the Kingdom of Hanover in 1814, and the personal union with the British crown lasted until 1837.
In 1692, Emperor Leopold I elevated Duke Ernest Augustus of the Brunswick-Lüneburg line of Calenberg, to the rank of prince-elector of the Empire as a reward for aid given in the Nine Years' War. There were protests against the addition of a new elector, and the elevation did not become official until the approval of the Imperial Diet in 1708. Calenberg's capital Hanover became colloquially eponymous for the electorate; however, officially it used the name Chur-Braunschweig-Lüneburg of the entire ducal dynasty.