While it is often thought that British military engagement in northwestern Europe ended with Waterloo in 1815 and resumed, a century later, with the First World War in 1914 – with a few periods of invasion anxiety surfacing around the middle of the 19th century –the men of 1814-15 shaped a century of relative stability through skilful diplomacy, strategic choices, and consistent policies, focussed on maintaining sea control to enable effective economic warfare, and deny the Belgian coast, Scheldt Estuary, and Antwerp to a major rival, initially France, and, by 1900, Imperial Germany.

After 1815 British statesmen and military strategists focussed on the threat posed by a succession of ambitious – but unstable – French regimes anxious to generate domestic credibility through diplomatic and military success, public art, and imperial expansion. French rulers from Louis XVIII to Louis Napoleon III sought domestic support through the pursuit of glory, even if the French people preferred peace, prosperity, and political accountability. The focal points of French ambition were the lost provinces beyond the Rhine, influence in Italy, and the recovery of Belgium. The last would enable France to base a fleet in the Scheldt Estuary, as Napoleon had done between 1801 and 1809, threatening an invasion of Britain, which would paralyse Britain’s ability to act on the continent.

In truth, the Napoleonic invasion threat had never been serious: France could not secure command of the sea, and the emperor knew that committing 100,000 men to a risky invasion across seas commanded by the Royal Nay would encourage Austria, Prussia and Russia to attack. In truth he was bluffing, to keep most of the British field army tied to home defence. In 1809 Britain removed the threat with an amphibious raid, landing 40,000 troops at Walcheren and destroying the critical naval base at Vlissingen on the Scheldt Estuary. This success released much of the British regular army to fight in Iberia, leaving home defence to militia and volunteers.

In late 1812 Napoleon’s disastrous retreat from Russia raised the possibility that 20 years of existential conflict might be coming to an end, prompting a remarkable group of British statesmen to plan for peace. Prime Minister Lord Liverpool, Foreign Secretary Lord Castlereagh, and General Arthur Wellesley, who became Duke of Wellington in May 1814 – were veterans of the long war. They understood that there could be no secure peace for Britain if France controlled northern Flanders and the Scheldt. Working with cabinet colleagues, senior admirals, and City of London financiers, they used the peace process to shape or ‘order’ a post-Napoleonic continent, to reduce the cost of defence by reducing the strategic threat to Britain from northwest Europe, enabling the recall and demobilisation of British troops from Europe, while preserving the legal power to impose maritime economic blockades, the critical strategic tool in the British arsenal. Between 1793 and 1814 economic warfare crushed the economies of Russia, much of central Europe, and ultimately France. When bankruptcy forced Russia to leave Napoleon’s ‘Continental System’, a pan-European blockade of Britain, Napoleon launched his disastrous 1812 campaign to force the Czar it back into the system.

British postwar policy was designed to reduce expenditure, to manage the immense debt burden incurred since 1793. The warfare state of 1793-1814 had to be dismantled to save the country from economic ruin, as Lord Liverpool stressed. Britian could manage the ‘ordered’ Europe created at the Vienna Congress (1814-15) from offshore. This required removing Belgium from France, denying the Scheldt Estuary where Napoleon had assembled a great fleet of battleships and transports to threaten an invasion of England. Britian secured those objectives before the Congress assembled at Vienna. Belgium would join the Dutch Republic in a ‘United Kingdom of the Netherlands’ under a Dutch King closely aligned with British interests.

When Napoleon he abdicated in April 1814 Russia, Austria, Prussia, and a restored Bourbon France accepted the British project to redraw the map of Western Europe. While Liverpool was anxious to reduce costs and withdraw from the continent, Wellington, as Ambassador in Paris, prepared a strategy to secure Antwerp, the Scheldt, and Belgium – in that order – against a new French invasion – relying on alliances and a new line of forts. In 1815 the Duke used a ‘system’ he had shaped in September 1814, combining British, Hanoverian, and Dutch/Belgian troops to hold Napoleon on the field of Waterloo, a superb defensive battlefield that had been studied and noted by Marlborough a century before during the War of the Spanish Succession. His Prussian allies delivered the coup de grace,  destroying Napoleon’s army removed the need for Britijn to maintain wartime levels of defence expenditure.

The Duke’s ‘system’ would remain in place for almost a century – relying on the support of Britain’s allies, who expected Wellington and a British army would appear if France invaded Belgium. In Government Wellington used his immense personal prestige to reduce the size of the army – accepting a degree of strategic risk to secure economic recovery. Naval funding was similarly reduced, because the only other major drain on the national economy – paying interest on the immense National Debt – was essential to maintaining Britain’s international credit rating. The navy’s battlefleet was modernised, the dockyards rebuilt, but manpower was cut. Critically old strategic risks were solved by new technology, steam ships, artificial harbours, at Dover, Portland, Dublin, and Holyhead, railways, telegraphs cables and mass-produced weapons.

Post-war British strategy still depended on sea control to secure food imports, prevent invasion, and impose economic pressure any hostile power, if France, Russia or the United States invaded Belgium, India, or Canada. The Low Countries remained the focal point of British policy in Europe for the next century. In 1830 Belgium rejected Dutch rule. Prime Minister Wellington took control of a process that would deliver a neutral state guaranteed by the five Great Powers, the Treaty of London, finally signed in April 1839. Belgian neutrality and territorial integrity neutralised the Scheldt Estuary and a French invasion of Belgium would be resisted by the other four powers.

However, France, under King Louis Philippe (1830-1848), remained a restless, unstable power, looking to recover la gloire, and lost status in battle. Successive French regimes pursued international prestige, creating political instability. The people wanted bread and a vote: their leaders offered war, increased taxes, and another generation of human sacrifice. Revolutions in 1830, 1848, and 1851, saw the country try two royal regimes, another Republic, and a Second Empire: all four failed, the last catastrophically on the field of Sedan in 1870.

In 1840 public statements that France would cross the Rhine prompted Frederick William IV, King of Prussia, to revive the ‘Wellington System’, summoning the Duke to command his armies, renewing the Waterloo partnership. Wellington accepted the offer, with Government approval. In the event his name was enough to deter the French aggression: but had war come he would have taken a small army to Europe, approximately 25,000 men, and repeated the strategy of 1815, meeting the French in southern Belgium at the head of a coalition force. As Commander of Chief of the Army from 1841 Wellington tried to increase army reserves, to release regular troops for this European role. A weak economy and the politics of the Corn Laws restricted improvements until the late 1840s, when fear of a steam-powered French invasion created a public enthusiasm for increased defence spending. By 1850 the Navy, largely steam propelled and supported by costly new artificial harbours at Dover, Harwich, Portland, Plymouth, and Alderney, was prepared to secure command of the English Channel in a war, block an invasion, and ultimately demolish French naval bases from the sea. In September 1852 Wellington secured a new Militia Bill, creating a paid reserve force which would man home defences in wartime, releasing regular troops for European service.

British strategic power would be demonstrated in the subsequent Crimean War (1854-56). In October 1854 the British Expeditionary Force of 25,000 men created by Wellington’s measure laid siege to Sevastopol, alongside French allies, destroying a major naval base that threatened Istanbul, and British control of the Mediterranean. Having captured Sevastopol British Royal Engineers systematically destroyed the entire naval base, including the massive dry docks.

The main naval arena of the war was in the Baltic, where the Russian capital St. Petersburg was blockaded and threatened, while other Russian fortresses were destroyed by long-range precision bombardment, using steam powered gunboats, mortar vessels and rocket boats, without very few casualties. After Sevastopol fell Britian assembled a ‘Great Armament’ of coast assault warships was prepared for the 1856 Baltic campaign, including gunboats, the world’s first ironclad warships, and an armada of floating workshops, and depots – ready to attack St. Petersburg. Bankrupted, and beaten Russia agreed to demilitarise the Black Sea, and return Ottoman territory. Britain celebrated victory with a spectacular Royal Fleet Review at Spithead in the Solent on 23 April 1856, St. Georges Day. It demonstrated coastal bombardment of Southsea Castle, and displayed a steam battlefleet, in the presence of the queen, the diplomatic corps from London, and journalists, ensuring the new form of naval power was broadcast widely – as the Times declared ‘a new system of naval warfare had been invented’ one that could reach deep inland’. The message was clear to any nation with an exposed coast, especially those who needed to be reminded that British sea power could reach far inland, notably primarily the United States and Russia, but Louis Napoleon IIII chose to compete, inaugurating the massive dockyard and base at Cherbourg in August 1858 – an overt challenge to British naval dominance. Louis Napoleon hoped he could intimidate the British into supporting his plan to redraw the map of Europe, to serve France. That delusion collapsed when the British rejected his agenda and used the opportunity he had provided to fine tune their plans for an attack from the sea, using new rifled artillery and armoured ships. The defences of Cherbourg had been overtaken by new technology. The following year a million British men become part-time Rifle Volunteers soldiers, their military merits were less important than the spectacle of a nation in arms. The invasion scare released defence funds to crush a brief French naval challenge in the shipyards, winning a costly naval arms race, with the radical new battleship HMS Warrior demonstrating British technological dominance. These measures placed national security beyond doubt.

In 1870 the Franco-Prussian crisis and conflict revived British concerns for the neutrality of Belgium. British concerns that France would win the war, and seize Belgium, promoted Prime Minister William Gladstone, to mobilise 50,000 troops along with a naval force – to secure Antwerp and the Scheldt Estuary. He warned Paris and Berlin that if either army crossed the Belgian border they would be at war with Britain. The rapid collapse of the French Empire after its defeat at the Battle of Sedan in September 1870 (and the subsequent abdication of Napoleon III) removed that risk, but this revival of the ‘Wellington System’ [using troops, fleets and diplomacy to maintain a stable European system that served British interests, reminded Europe of Belgium’s special status in British policy. When Imperial Germany became a threat in 1900 Colonel Charles Repington, British Defence Attaché in Brussels and the Hague, stressed the need to revive the ‘Wellington System’, declaring that keeping potentially hostile Great Powers out of the Low Countries had ‘been one of the most cherished, consistent and consecutive traditions of our foreign policy’, essential to the maintenance of British command of the sea. Such arguments shaped the new British Expeditionary Force (BEF) of 1907, a home-based five-division strike force prepared to defend Antwerp if Germany invaded Belgium. Yet when Britain declared war in August 1914, after Germany it had violated Belgian territory, the BEF was redirected to support the French. As a direct result Antwerp fell, creating a major strategic risk. The politicians who acted in August 1914 had forgotten the experience of 1870.

After a century  of peace, secured by sound policy, backed by occasional displays of raw power, the ‘ordering’ and ‘offshore balancing’ methods applied by Castlereagh, Liverpool, and Wellington were ignored. The fruits of sound policy, the development of British global economic power, and the reduction of the National Debt – were reduced to irrelevance within months, as wartime spending ballooned, and British men were conscripted into the army for the first time. The unique elegant and above all successful maritime strategy of 1815-1914, using money, diplomacy, and sea control to control Europe was abandoned, replaced by a German ‘way of war’ that relied on raw military power and descended, quickly, into total war. The strategic impact of this failure was catastrophic –Germany would use the naval bases at Ostend and Zeebrugge for devastating assaults on British commercial shipping in the English Channel, which came close to winning the war. Wellington would have been horrified.