Britain tremendously expanded its extra-European empire during the Napoleonic period, acquiring Malta, the Cape of Good Hope, Ceylon, and parts of India. It also consolidated its hold over Ireland with a parliamentary union in 1800–1; the relationship with Hanover was the last remaining dynastic tie of the early modern variety. Even this seemed over, as successive occupations of that country by foreign powers effectively interrupted the two countries’ political relationship. In so far as Hanover's dilemma indirectly resulted from British policy (the failure to evacuate Malta as promised in the Treaty of Amiens), dynastic union continued to attract attention during its hiatus. The ensuing debate in Hanover was unprecedented in scope. Berlepsch's heirs built upon his charge that British empire over Hanover had exacerbated social inequality, while ministerial authors argued that personal union had rendered the French invasion illegal under international law. British interest in Hanover only picked up after France briefly yielded the electorate to Prussia in 1806. Britain's consequent declaration of war against Prussia registered unhappiness with permanent exclusion from the continent, although it prompted howls of protest from opponents of dynastic union. Had Hanover remained under foreign domination, these discussions might have constituted nothing more than an interesting postmortem for dynastic union. But because Hanover returned to the British monarchy in 1813, they greatly influenced the two countries’ future relationship.

As the nineteenth century opened, Britain was reminded of Hanover's vulnerability. Prussia occupied the electorate in the spring of 1801 at the instigation of Russia's tsar, who hoped thereby to forestall British attacks upon neutral shipping in the Baltic. For a second time, British policy had exposed Hanover to a foreign occupation. Charles James Fox reversed his earlier opinion of the Fürstenbund era, observing that though ‘in this instance Hanover has suffered on account of her being under the samesovereign as Great Britain … she is not in any way an ally of ours and much less a part of us’.