This City Founded in medieval times on the left (south) bank of the river Leine, Hannover was a small village of ferrymen and fishermen that became a comparatively large town in the 13th century as a natural crossroads. In a time of relatively difficult overland transportation, its position on the upper navigable reaches of the river positioned it for increased trade and growth. Connected to the Hanseatic League city of Bremerhaven via the Leine river from its place near the southern edge of the wide central German plains to its north and situated to the north and west of the Harz mountain barrier to the southeast it enjoyed a mountain skirting "crossroads" position in mule train dominated based east-west land traffic. Hanover essentially acted as a gateway to the Rhine, the Ruhr and Saar River valleys and their industrial areas to the southwest, for the plains regions both to its east and north, as well as overland traffic skirting the Hartz between the Low Countries and Saxony or Thuringia.In the 14th century the main churches of Hannover were built, as well as a city wall with three town gates to secure the city. With the coming of the beginnings of industrialization in Germany, trade in iron and silver from the northern Hartz mountains increased the city's importance.
In 1636, the Elector of Calenberg, the new Duke of Brunswick-Lüneburg, decided to move his residence to Hanover. His electorate was afterwards known as the Electorate of Hanover (see: House of Hanover). His descendants would later become monarchs of Great Britain (after 1801, monarchs of the United Kingdom of Great Britain and Ireland). The first of them was George I, who ascended to the British throne in 1714. Three kings of Great Britain, or the United Kingdom, were at the same time Electoral Princes of Hannover.
During the time of the personal union of the crowns of the United Kingdom and Hanover (1714–1837), the monarch rarely visited the city. In fact, during the reigns of the final three joint rulers (1760–1837), there was only one short visit, by George IV, in 1821. Usually, a viceroy represented the monarch in Hanover.
During the Seven Years' War on July 26, 1757, the Battle of Hastenbeck took place near the city. The French army defeated the Hanoverian Army of Observation, leading to the city's occupation.