What if Napoleon had conquered Britain? We avoided the extreme, continental ideologies of the 20th century

Napoleon’s conquests of other countries provide a clue — notably so if there was strong resistance — most obviously Spain after it was seized in 1808. Such resistance was certainly planned in Britain. Documents from figures such as Thomas, Lord Pelham, Home Secretary from 1801 to 1803, as well as Dundas’s 1796 memo, indicate plans to contest bitterly any French advance from the landing sites, including using scorched earth policies. (Major-General Sir David Dundas would serve as Commander-in-Chief from 1809 to 1811.)

To this end, and in the face of repeated invasion fears, there was a large-scale mobilisation of males into militia and volunteer units, and these were extensively trained. Numerous barracks and Martello towers were built along the south coast. So Britain would have fought, and would have fought hard.

French troops landed in Wales in 1797 and, on a greater scale, in Ireland in 1798. These incursions were swiftly suppressed by locally-available forces, which suggests that far more French troops would have been required for any invasion to succeed. That, indeed, had been the invasion plan in 1759 and 1779, during earlier conflicts. Any French advance from the South Coast would have been contested in the Weald and then again at the Thames. There was also a reserve centre of government in Northamptonshire, to carry on the fight if London fell.

The French advance would not have had the support of air power, airborne troops or mechanised forces, as was the prospect Britain faced in 1940.

If the country had still been conquered, then the hypotheticals open up further. Napoleon’s hostile attitude to Britain, which he regarded as crucial to the opposition throughout Europe, would scarcely have eased as opposition grew there. There were three options used by Napoleon for the lands he conquered, and none was attractive for those defeated. Incorporation in France was one option. This might seem implausible in the case of Britain, but given that Napoleon adopted this method very widely, including for example for the Hanseatic Towns, Dalmatia and, eventually, the Netherlands, it could well have been adopted here. It would have meant military government.

Secondly, there was the option of installing a member of his family, or a close ally, as ruler, as with Naples, Spain, Westphalia, Sweden (with the Frenchman Bernadotte as Regent) and, for a while, the Netherlands. There was no-one available, however, who would have been acceptable in Britain, and no member of the British Royal Family who could have been brought forward.

Thirdly, as with Austria in 1805 and 1809, and Prussia in 1806, they could leave the existing ruler in power but drastically curtail their position, notably by greatly annexing territory, but also by other constraints. This would scarcely have been easy and in Prussia provoked the anger that encouraged an anti-French reaction in 1812-13. It is difficult to see either George III or the Prince Regent as being willing to accept this role. Moreover, unlike in Spain, where the rift in the royal family had provided the French with options, in Britain the divide between George III and the Prince of Wales had greatly eased by this time.

Napoleon would have needed a quiescent Britain if he was to turn against Continental rivals, but, as in Spain from 1808, a significant occupation army in Britain would have compromised that outcome. Yet Napoleon was not a ruler able to secure quiescence, in large part because, despite the rhetoric of Enlightenment, his rule was oppressive and extortionate. The choice, whether annexed or “allied”, was a poor one. As with Hitler, the inevitable consequences of rule by France was manpower being conscripted and resources seized.

This avarice encouraged opposition which, in turn, was treated harshly. In Lombardy in 1796, Napoleon used summary executions and the burning of villages. Such insurgencies were not new, but they became more important from 1792-1815, in part because the French Revolutionaries and Napoleon transformed, destroyed or took over existing power structures, and also because they accelerated processes of change that much of the population already found inimical.

In particular, French attacks on the Church and Christian practices, let alone full-scale atheistical de-Christianisation, were far from popular, challenging both established beliefs, interests and senses of order, continuity, identity and legality. This helped to contextualise the pressure of meeting onerous French demands for supplies and conscripts for their army, and their seizures of goods and money.

The net effect was a widespread opposition and lawlessness, with, in addition, insurgencies of various types seen across larger areas of Europe as French forces advanced, for example in Calabria in 1806. The French responded with troops, which were referred to as flying columns, by the use of the gendarmerie (mobile armed police), and by recruiting local allies. In 1798, despite what Napoleon saw as the introduction of Enlightenment policies into Malta after he seized it, the island rapidly rebelled in large part due to an insensitive treatment of the Church, which was always a poor strategy, as well as higher taxation. Because of its history of opposition to France, Britain would probably have been far worse-treated.

In the British Isles it is very likely that, had Napoleon invaded, he would have found local allies, with more in Ireland than anywhere else. They would not have relied on these rebels to fight for them in England — that was a job for the Grand Armée — but once established, the French would very much have sought assistance in order to get government to work. Moreover, they would have sought to withdraw most of the invading army in order to operate elsewhere.

What French control would have meant would have varied greatly depending on the particular French government in question, and this would have affected the likely supporters in Britain. The radicals of the London Corresponding Society and other such bodies would have worked with the republican regimes of the 1790s but have found an imperial Napoleon far less conducive.

Nevertheless, convenience, self-interest and ideology would have won him some support, as was also the case with the Kingdom of Italy established in 1805. The longer the new order was entrenched, the more likely that there would have been collaborators, although it would have varied. Some of the poets and painters would doubtless have helped decorate the new regime, but they would have been of scant consequence, as anyone with a suitably neo-classical palette would have qualified. Christian Tories, such as Jane Austen, would probably have remained unpublished.

In the ideological sphere, Napoleon’s support for the reintroduction of slavery and the suppression of Haiti would have caused problems for some of the fellow-travellers, but their consciences would doubtless have been flexible, prefiguring those of the historians who have praised Napoleon. Charles James Fox might have justified co-operation on a needs-must basis, and would have certainly been a convenient figurehead for a ministry. The latter would have probably contained “men of business” but the subordination of mercantile Britain to French interests would have exposed their political weakness as quislings able only to implement dictates determined in Paris.

Ultimately, most of the Whigs would probably have found the reality of Napoleonic rule highly unwelcome. The position of his British supporters would have been greatly weakened by the burdens arising from his expectations of support for his imperialism elsewhere.

The net effect would have been to make British politics far more divisive, both then and subsequently. Conservatism and nationalism would have been closely linked, and the radical tradition associated with harsh foreign rule. In Europe in 1816-48, and to a degree thereafter, there was a divisive political tension that owed much to the legacy of Napoleonic rule. Britain was spared that legacy, and there was only a comparable dissension in Ireland. However much it owed to the silver sea and the Royal Navy, and the security these offered, this difference contributed to British political exceptionalism.

The divisions between liberalism and conservatism that were so bitter in much of Continental Europe in the 19th century — literally then a matter of life and death — played a role in their 20th-century counterparts of Left and Right, as did the legacy of past practices of co-operation or resistance with conquerors. In Britain, things turned out differently, with the centre holding firm for a patriotic affirmation of national sovereignty against extremism of Left and Right. And this owed much to the fact that Britain was able to avoid the rule of Napoleon Bonaparte.