Britain has not been successfully invaded since 1066. This banal statement is interesting not for the ‘what every schoolboy knows’ truth it contains but for what it does not say. For is it not astonishing that an island nation-state, of important second rank from the sixteenth to the eighteenth century and a world power thereafter, should have successfully resisted attempts at conquest by its foreign enemies for four centuries? The proposition looks even more amazing once one realises how many invasion attempts were actually mounted against the British Isles. How was this achievement possible?

The cliché answer is that British sea power prevented successful invasion. Like most clichés, this expresses an essential truth. But was sea power a sufficient condition for Britain’s security or merely a necessary one? Does the mere possession of naval superiority in the Channel guarantee immunity from invaders or are other factors involved? What role can we assign to fortune, to contingency, to leadership, to mistakes and miscalculations and, most importantly, to the weather? And if British hegemony in the waters around these islands is the complete and sufficient answer to the problem, how do we explain French failure in 1692 and 1779 when they did possess local naval superiority in the Channel?

The issue of British sea power begins to look even more intriguing once we grasp that the power of the Royal Navy may even have been more important as the cause of the numerous invasion attempts than as the instrument of their defeat. For it was only when Britain became a sea power of the first order that she became important enough to be worth invading. Moreover, only when naval power was perceived as an important element in general military strength were the real problems involved in invading the British Isles seen clearly.

There are strong grounds for saying that the invasion of the British Isles, and especially of England, became an important element in the consciousness of her continental rivals only with the discovery of the New World and the consequent replacement of a primarily Mediterranean orientation for Europe with an Atlantic one. In geopolitical terms the discovery of the Americas transformed England from a marginal power on the fringes of a continent into a primary actor in the new struggle for the wealth and trade of the Americas. It is quite true that from the time of the Tudors onwards the British Janus looked both to the wider world, where it was building up an empire, and to Europe, where its interest was to see that no one nation dominated the continent. But it is my contention that it was always the imperial factor and not the continental one that precipitated threats of invasion.

The invasion of Britain, then, becomes a serious issue only with the dawning of what in historiography is usually referred to as the 'early modern’ period. Before that time both motive and opportunity were lacking for an invasion in the sense with which we are concerned in this study. Such invasions as had taken place in the ancient and medieval periods were different in kinds, being either arbitrary extensions of the Pax Romana like Caesar’s incursions in 55-54 BC and Claudius’ permanent occupation of the island in AD 43, or aspects of a general migratory phenomenon, like the advent of the Saxons in 449, the Angles in 547, or the successive waves of Danes from the eighth to the eleventh century. Significantly, perhaps, historians of Rome have been notoriously hard put to it to suggest a cogent motivation for the Roman conquest and occupation of the island.

Even the Norman Conquest of 1066 came about as a result of a dynastic dispute and was not connected with issues of sea power. Thereafter, until the discovery of the Americas, the possession of Normandy by the English kings made the idea of a descent in force on England seem impracticable even at the level of military expediency. This was quite apart from the consideration that the lack of centralised power in the feudal era made the logistics of gathering together a sufficient number of troops and transports for the crossing of the Channel an awesome task. During the Middle Ages, whenever a foreign force was able to set foot on English soil it was quickly driven out again, through inability to land troops in sufficient numbers and with adequate provisions. So it was with the Danish raid in 1135, the 1359 adventure when a party of French sailors sacked Winchelsea and then re-embarked immediately, and the more formidable assault on Portsmouth in 1377, when the French burned the town after landing on the Isle of Wight.

Although these early experiences do not constitute invasions in the true sense, they repay study for the lessons they offer for the era of invasions proper. Even though before the sixteenth century we are dealing merely with armies crossing the Channel unopposed by an enemy fleet, some factors had made themselves felt that were to be constants thereafter. First, there was the consideration that a successful invasion seemed more likely if there was collaboration between two continental powers. The French king Philip, foe of Richard the Lionheart, had grasped this when he tried to collaborate with King Knut of Denmark in 1193 on a plan for a landing in England. So too had Charles V during the Hundred Years’ War when he made a similar approach to King Waldemar Atterdag of Denmark. There was an echo of these schemes a hundred years later when Charles VII of France made overtures to King Christian of Denmark. The simple truth had been grasped that a two-pronged invasion would increase the problems of the defender almost exponentially. Although there had not been collusion in 1066 between Duke William of Normandy and Harald Hardrada of Norway, it was their almost simultaneous descent on England at points hundreds of miles apart that had done for Harold Godwinson. Ever afterwards the shrewdest invaders tried to compass simultaneous descents at different landfalls in the British Isles, and it was the abiding nightmare of British governments that they might have to repel two sets of enemies at once.

The other lesson of 1066 was the unreliability of the weather around the British Isles. William of Normandy had waited on the French coast all summer for the winds to turn in his favour. Though Gibbon was later to assert that wind and waves invariably favoured the best navigators, this seems no more than a gloss on the fact that storm and breeze usually favoured the British defenders, to such a point indeed that in a later era the legend of a ‘Protestant wind’ was to arise. Whether the enemy appeared off the British coast in summer (as in 1588 or 1779), or in winter (as in 1744 and 1759), the weather always seemed to lend a hand. And anyone who was involved in the 1979 Fastnet race does not need to be told of the fury of the Atlantic when it surges at gale strength around British coasts. The first recorded visitor to these shores (and incidentally the first Polar explorer), Pytheas of Massilia, who circumnavigated Britain sometime in the decade 330-320 BC, reported waves conservatively estimated by modern scholars to have been sixty feet high from trough to crest in the Pentland Firth. Such seas are by no means extraordinary in British waters. Storms and mountainous waves provide a powerful obstacle to any enemy and are the natural bonus an island lying off a great ocean enjoys. Japan similarly remained uninvaded in the past thousand years and had an even more formidable ally in this shape: the fearsome typhoons of the Pacific that destroyed the Mongol invasion fleet of 1281 and battered US warships in 1944-45.

The advantage of collaboration with an ally, and the fearsomeness of the seas: these were the two lessons from an earlier era brought forward to the age of sea power proper. How then did the situation in the sixteenth century, when Philip II launched his ‘invincible Armada’, differ from that in all previous ages? The answer is that in the earlier period no problems of naval strategy were involved. The invaders simply transported an unopposed army across the North Sea or the Straits of Dover. If enemy ships were encountered, armies boarded each other’s vessels and fought hand-to-hand combat. Naval strategy proper only began when ships acquired artillery and became floating batteries. Until that time naval battles were simply infantry contests at sea, complicated by the fact that the arena of conflict itself, the ship, could be rammed and sunk. Put another way, modern naval strategy is a by-product of the invention of gunpowder and bullets – precisely the technological breakthrough that enabled Europeans to establish themselves in the New World. The Vikings had earlier been dislodged from their precarious North American footholds for lack of such technical superiority.

So the invention of the gun, part of the technological ‘takeoff’ that made possible the great voyages of discovery of the late fifteenth and early sixteenth century, has an intimate connection with the study of island invasions. With the coming of firepower, navies automatically acquired a new significance. But their political significance for Britain is also enhanced, for now the navy becomes the principal means of defence against an enemy increasingly tempted to redress the balance of power in the New World by striking at the English enemy in its heartland.

From the sixteenth century onwards the problem of invading an island like Britain or Ireland focused on what to do about the fighting ship – that lethal floating artillery platform. The invading armies, which in a previous era could cross unopposed, now had to be protected against destruction in mid-sea. Increasingly the enemy’s problem narrowed to that of protecting his transports.

Basically there were three strategies available. The first was the 1588 Armada strategy: the combined operation when fleet and transports sail together in close formation. For this to succeed two things were essential: an overwhelming superiority at sea; and the closest possible liaison between army and navy commanders. Historically, achieving naval superiority against the Royal Navy proved impossible for Britain’s enemies for all but brief moments, such as in 1690 and 1779. And it is worth pointing out that this naval superiority had to be of a very high order, both to leave a surplus of ships for the protection of home ports and waters and to have the necessary freedom to engage the Royal Navy without restraint. If the rival fleets were roughly equal in strength, the invader would be under the almost prohibitive handicap of having to fight a fleet action while at the same time manoeuvring to protect the transports.

True, superiority might in principle be achieved by a coalition of enemy fleets, such as those of France and Spain, but here liaison between army and navy becomes paramount. Because of inter-service rivalry the necessary close collaboration between army and navy was achieved only rarely even within the armed forces of a single nation-state. Where two or more nations combine their land and sea forces, the possibilities for disharmony through jealousy, pride, national honour and other reasons compound the basic problems and increase, almost geometrically, the likelihood of disaster.

For this reason the second strategy, that of prior and independent action by the invader’s battle fleet, was generally considered a more fruitful option. The independent action might consist of searching out and destroying the defender’s fighting ships before launching the transports. Given the normal superiority of the Royal Navy, this was largely a theoretical option. More feasible was the tactic of putting to sea with the men o’ war and hoping to lure the British fleet away from the invasion points while the transports slipped across the Channel unescorted. This was essentially the strategy adopted by Napoleon in his duel with Nelson during 1804-5. A variant on this was to attempt to split the defending fleet by making a number of simultaneous descents at different points on the British coastline, thus hoping to dissipate the defending ships. The French invasion attempt of 1759 was a classic illustration of this theme and its variations.

The third possibility for invasion was the surprise assault without a declaration of war – the tactic attempted by the French in 1743-44. The key to this was the utmost secrecy. Transports, warships, men and material, all had to be assembled without enemy spies being alerted. They would then be launched across the Channel suddenly and without warning. The possibilities of this sort of strategy foundering were all too obvious, especially as the assembling of sufficient resources in the ports of Normandy, Picardy and Brittany was, perforce, primarily a seaborne affair. On numerous occasions the Royal Navy intercepted ships ferrying stores or timber from one port to another – Cherbourg, say, to Le Havre, or Dunkirk to Boulogne.

This largely explains the persistent British obsession with Flanders throughout the era of ‘modern history’. ‘He who holds Flanders holds a pistol at England’ was one of the sustained and enduring clichés. The importance of Flanders lay in its superb and intricate inland waterway system of canals and rivers. An enemy in possession of the land of the Belgians could assemble a vast army inland and then convey it to Antwerp for immediate embarkation for England. If Flanders was in hostile hands, then, given the possibility of a surprise attack, Britain would have to be on a permanent war footing, her fleets and armies constantly in readiness. Not only would this be a ruinous drain on British finances, but the uncertainty thus engendered would lead to political brittleness and social instability at home. This strategic imperative of a friendly or neutral Belgium accounted for much seemingly pointless British meddling in the system of continental alliances, and for the traditional policy of friendship with the Dutch.

This neat paradigm of three invasion strategies becomes slightly obfuscated with the coming of air power in the twentieth century, for now the invader has to think in terms of both sea and air power. Hitler’s 1940 strategy can be seen to be a fusion of the Armada and Napoleonic motifs. The Napoleonic element comes out in the attempt to destroy the RAF, analogous to luring away the British fleet in an earlier era. The Armada element can be seen in the reliance on overwhelming power brought to bear against the defending fleet, but this time by the Luftwaffe rather than Spanish galleons.

What general strategies could Britain bring to bear against the threat of invasion? Espionage was one obvious means of defence. From Elizabeth's time the British secret service, virtually created by Walsingham, acquired an enviable reputation, sometimes far outstripping its actual achievements. Another means of ‘offensive defence’ was to attempt to deny actual or potential enemies vital supplies of timber, pitch or foodstuffs, so that their fleets could not be fitted out or provisioned. In wartime this economic warfare could be tightened by the actual blockade of enemy ports. As for the navy itself, in Britain a professional approach to seafaring was encouraged in the officer class. In aristocratic England the fool of the family could find a career in the army, but rarely in the navy. The meritocracy in the Royal Navy that produced men like Captain Cook contrasted with the stultifying nepotism and grandee tradition in the French Marine before the Revolution, a tradition in which blood and rank were everything.

In actual warfare when engagement with the enemy was imminent, the Royal Navy used two main tactics. One was the pre-emptive strike, like Drake’s ‘singeing the King of Spain’s beard’ at Cadiz in 1587. The other was the preparation of a supplementary flotilla to deal with enemy transports. The reasoning was that even if the French or other enemies lured away the battle fleet by seeming to offer combat with their own warships, an ancillary flotilla of privateers and frigates would be ready to deal with unescorted transports trying to slip across the Channel. The emphasis here was not on bringing the enemy to battle but sinking him on the high seas.

The invasion of Britain in the modern period thus settled into a duel of wits. In the Admiralty in England or the Ministry of Marine in France lengthy memoranda were produced, dealing with every conceivable hypothetical situation to be encountered in planning or obstructing a descent on the British Isles. This ‘war gaming’ undoubtedly refined the strategic thinking on both sides and led to significant advances in the understanding of how sea power operates. But until the era of steam, and even afterwards, there was still an ancient factor that could upset all calculations: the weather. In 1588, in the first real invasion attempt of the modern era, both sides were to learn this to their cost.


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