Electorate of Brunswick - Lüneburg The Electorate of Hanover ( formally the Electorate of Brunswick - Lüneburg ; , colloquially " Kurfürstentum Hannover " or simply " Kurhannover " ) was the ninth Electorate of the Holy Roman Empire of the German Nation . It was a monarchy in Northern Germany , ruled by the House of Hanover , cadet branch of the House of Welf , which then ruled and earlier had ruled a number of principalities , which had several times been partitioned among several heirs from an earlier unitary territory named Brunswick - Lüneburg after the pertaining cities of Braunschweig ( Brunswick ) and Lüneburg ( Lunenburg ) . After 1705 , only two of these territories left : One was the Principality of Brunswick - Wolfenbüttel , which remained independent as the Duchy of Brunswick ( new title adopted in 1815 ) until 1918 . The other , the new Electorate , was based on the dynastic line of the Calenberg . With the ascension of its prince - elector as King of Great Britain in 1714 , it became ruled in personal union with Great Britain . As a consequence , a reluctant Great Britain was forced time and again to become involved with the fate of the German possessions of her King . However , internally , it remained a separately ruled territory with its own government and bodies . In 1814 , it was transformed into the Kingdom of Hanover , with the personal union with the British crown lasting until 1837 . Official name and other name versions . 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 War of the Grand Alliance . 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 . Then George I Louis had already succeeded his late father and furthermore had inherited the Principality of Lüneburg , whose dynastic line was extinct , in 1705 . Calenberg ' s capital Hanover became colloquially eponymous for the electorate ; however , officially it used the name of the entire ducal dynasty . In 1700 the territories forming the electorate introduced – like all Protestant territories of imperial immediacy – the Improved Calendar , as it was called by Protestants , in order not to mention the name of Pope Gregory XIII . So Sunday , the 18 February of Old Style was followed by Monday , the 1 March New Style . History . Link with Britain . In 1714 , George Louis became king of Great Britain , so that the electorate and Great Britain were ruled in personal union . The possessions of the electors grew in Germany as well , as they de facto purchased the formerly Swedish - held duchies of Bremen and Verden in 1719 . In 1728 Emperor Charles VI officially enfeoffed George II Augustus , who in 1727 had succeeded his father George Louis , with the reverted fief of Saxe - Lauenburg , which had de facto been ruled in personal union with Hanover and its one preceding Principality of Lüneburg since 1689 . In Hanover , the electoral capital , the Privy Council of Hanover ( electoral government ) installed a new ministry in charge of the Imperial Estate s ruled by the electors in personal union . It was called the " Department of Bremen - Verden , Hadeln , Lauenburg and Bentheim " . However , the electors spent most of their time in England . Direct contact with the electorate was maintained through the office of the German Chancery , situated in St James ' s Palace in London . Seven Years War . In the course of the Anglo - French and Indian War ( 1754 – 63 ) on North American colonies Britain feared a French invasion in Hanover . Thus George II Augustus formed an alliance with his Brandenburg - Prussian cousin Frederick II , " the Great " combining the North American conflict with the Brandenburg - Prusso – Austrian Third Silesian or Seven Years ’ War ( 1756 – 63 ) . In summer 1757 the French invaded Hanover and defeated George II ' s son William Duke of Cumberland , leading the Anglo - Hanoverian army , at the Battle of Hastenbeck and drove him and his army into remote Bremen - Verden , where in the former monastery of Zeven he had to capitulate on 18 September ( Convention of Kloster - Zeven ) . But George II Augustus denied his recognition of the convention . In the following year the British army , supported by troops from Brandenburg - Prussia , Hesse - Kassel and the ducal Principality of Brunswick and Lunenburg ( Wolfenbüttel ) expelled again the occupants . Hanover remained unaffected for the rest of the war and after its end peace prevailed until the French Revolutionary Wars started . The War of the First Coalition against France ( 1793 – 97 ) with Great Britain - Hanover and other war allies forming the coalition , didn ' t affect Hanoverian territory , since the first French Republic was fighting on several fronts , even on its own territory . However , men were drafted in order to recruit the 16 , 000 Hanoverian soldiers fighting in the Low Countries under British command against France . In 1795 the Holy Roman Empire declared its neutrality , comprising Hanover ; however , a peace treaty with France was under negotiation until it failed in 1799 . Brandenburg - Prussia , however , ended for its part the war with France by the Treaty of Basel ( 1795 ) , stipulating Brandenburg - Prussia would ensure the Holy Roman Empire ' s neutrality in all the latter ' s territories north the demarcation line of the river Main , including the British continental dominions of Hanover , Bremen - Verden , and Saxe - Lauenburg . To this end also Hanover had to provide troops for the so - called " demarcation army " maintaining the " armed neutrality " . Napoleonic era . In the course of the War of the Second Coalition against France ( 1799 – 1802 ) Napoléon Bonaparte urged Brandenburg - Prussia to occupy the continental British dominions . In 1801 24 , 000 Brandenburg - Prussian soldiers invaded , surprising Hanover , which surrendered without a fight . In April 1801 the Brandenburg - Prussian troops arrived in Bremen - Verden ' s capital Stade and stayed there until October of the same year . The United Kingdom of Great Britain and Ireland first ignored Brandenburg - Prussia ' s hostility , but when the latter joined the pro - French coalition of armed neutral powers such as Denmark - Norway and Russia , Britain started to capture Brandenburg - Prussian sea vessels . After the Battle of Copenhagen ( 1801 ) the coalition fell apart and Brandenburg - Prussia withdrew its troops . As part of the German Mediatisation of 25 February 1803 , the Electorate received the Prince - Bishopric of Osnabrück in real union , whose every second ruler had been alternately staffed by members of the House of Hanover since 1662 . After Britain – this time without any ally – had declared war on France ( 18 May 1803 ) , French troops invaded Hanover on 26 May . According to the Convention of Artlenburg ( 5 July 1803 ) , confirming the military defeat of Hanover , the Hanoverian army was disarmed and its horses and ammunitions were handed over to the French . The Privy Council of Hanover , with minister Friedrich Franz Dieterich von Bremer holding up the Hanoverian stake , fled to the trans - Elbian Saxe - Lauenburg , ruled by Britain - Hanover in personal union . Soon later the French also occupied Saxe - Lauenburg . In autumn 1805 , at the beginning of the War of the Third Coalition against France ( 1805 – 6 ) , the French occupational troops left Hanover in a campaign against Austria . British , Swedish and Russian coalition forces captured Hanover . In December the Empire of the French , since 1804 France ’ s new form of government , ceded Hanover , which it didn ' t hold anymore , to Brandenburg - Prussia , which captured it early in 1806 . On 6 August 1806 the Holy Roman Empire was dissolved , thereby doing away with the function of prince - electors electing its emperors . Thus the title of Elector of Brandenburg became meaningless for the Kingdom of Prussia . After it had turned against France , it was defeated in the Battle of Jena - Auerstedt ( 11 November 1806 ) , and France recaptured Hanover . Following the Treaty of Tilsit in 1807 the new Kingdom of Westphalia was founded , ruled by Napoléon ' s brother Jérôme Bonaparte , then including territories of the former Electorate of Hesse - Cassel , the ducal Brunswick - Lüneburg ian principality Brunswick - Wolfenbüttel , and formerly Prussian territories . In early 1810 Hanover proper and Bremen - Verden , but not Saxe - Lauenburg , were also annexed by Westphalia . In an attempt to assert the Continental System the French Empire annexed in late 1810 all the continental North Sea coast ( up till Denmark ) and the areas along the sections of the rivers navigable for seagoing vessels , including Bremen - Verden and Saxe - Lauenburg and some adjacent territories of Hanover proper . However , the government of George III did not recognise the French annexation , being at war continuously with France through the entire period , and Hanoverian ministers continued to operate out of London . The Privy Council of Hanover maintained its own separate diplomatic service , which maintained links to countries such as Austria and Prussia , with whom the United Kingdom itself was technically at war . The Hanoverian army was dissolved , but many of the officers and soldiers went to England , where they formed the King ' s German Legion . The Legion was the only German army to fight continually during the whole Napoléonic wars against the French . French control lasted until October 1813 when the territory was overrun by Russian troops , and the Battle of the Nations at Leipzig later the same month spelled the definitive end to the Napoléonic client state of Westphalia , as well as the entire Confederation of the Rhine , after which the rule of the House of Hanover was restored . The former electorate became the Kingdom of Hanover , confirmed at the Congress of Vienna in 1814 . Electors of Hanover . The Electorate was legally bound to be indivisible : it could add to its territory , but not alienate territory or be split up among several heirs – as used to be the rule before , having led at times to a multitude of Brunswick - Lüneburg ian principalities . Its succession was to follow male primogeniture . Since this was against the Salic law , then valid for the ducal family , the change needed imperial confirmation , which Emperor Leopold I granted in 1692 . In 1692 , at the upgrading to the rank of electorate , its territory comprised the Brunswick - Lüneburgian principalities of Calenberg and Grubenhagen , which the line of the former had already inherited in 1665 . But until the confirmation of the electorate by the Imperial Diet in 1708 the Calenberg line further inherited the principality of Celle in 1705 . Further included were the earlier acquired counties of Diepholz and Hoya . Although the Holy Roman Empire was dissolved in 1806 , George III ' s government did not consider the dissolution to be final , and he continued to be styled " Duke of Brunswick - Luneburg , Arch - treasurer and Prince - Elector of the Holy Roman Empire " down to 1814 .