Recognising this potential weakness, French forces made concerted attempts to defeat Hanover during the Seven Years' War, overrunning the Electorate in 1757 before being driven out by Ferdinand of Brunswick and repulsed at the Battles of Krefeld and Minden.

[4] The renewal of the conflict led to Napoleon gathering a large army on the Channel coast of France, poised to attempt an invasion of Britain.

[5] The Electorate was defended by the Hanoverian Army and locally raised militias under the Duke of Cambridge, George III's son, and Count Wallmoden.

The French takeover of Hanover, which Prussia itself coveted, was one of the factors that drove Prussian king Frederick William III going to war against Napoleon in 1806, leading to its own occupation and the loss of many of its own territories at the Treaty of Tilsit in 1807.

Much of the territory of the electorate was subsequently incorporated into the Kingdom of Westphalia, ruled by Napoleon's younger brother Jérôme Bonaparte, with the northern area around Bremen becoming departments of France.