The Battle of Trafalgar (21 October 1805) is a high point in British history - a famous victory, a famous tragedy, an event that everybody knows something about and everybody celebrates. It is rather surprising, therefore, that there is no easy consensus as to what it actually achieved.
At the time, and for long afterwards, the British believed that in the hour of his death Nelson had wrecked Napoleon's invasion plans and ensured Britain's ultimate victory over Napoleonic France.
In contrast, French historians preferred to dismiss the battle as an unfortunate but essentially marginal affair, not to be mentioned in the same breath as Napoleon's smashing victories at Ulm and Austerlitz in the same year as Trafalgar - victories that drove Austria and Russia from the war, and yet again confirmed France's unchallenged domination of Europe.
Amongst historians to-day, these opinions have changed surprisingly little, but they have changed sides. Distinguished French scholars such as Jean Tulard, the great authority on Napoleon, agree that,
'... after Trafalgar the emperor was beaten, though he did not yet know it.'In Britain, meanwhile, historians for the past half-century have agreed that Trafalgar only confirmed what everybody had always known. Britain controlled the sea after Trafalgar, but then she had always controlled the sea, and would have continued to do so even if Napoleon's Combined Fleet had not put to sea in October 1805.
They have also often cited Trafalgar as the ultimate (if not the only) piece of evidence for their overall view of Britain's strategic situation in relation to the powers of continental Europe over the centuries. Their interpretation has been that British sea power, though certainly necessary for survival in the face of aggression from France, was not sufficient for victory over Napoleon, and that ultimately it was Wellington and the British army, fighting alongside a great coalition of military powers in 1814 and 1815, that secured Britain's triumph.
They believe that the great issues between the nations of Europe have always been decided by massed armies clashing on the plains of Flanders and Westphalia, while sea power has played only a supporting role. Articulated by eminent scholars such as Sir Michael Howard and Piers Mackesy - who themselves fought in the analogous campaigns of 1944 and 1945 - this has been the dominant view for half a century. This is strategic history for the age of NATO and the British Army of the Rhine.
We can hardly doubt that this judgement is correct, applied to the circumstances of 1815 or 1945. If it is necessary to fight a war of annihilation, as it was against Napoleon and Hitler, if nothing will do but the conquest and overthrow of the enemy regime, then certainly sea power alone will never suffice.
As a general interpretation of Britain's strategic situation over many centuries, however, the argument is a good deal less persuasive, for such wars have in fact been uncommon in history. Most British wars have been fought for more limited objectives, and the first gift of sea power was that these wars were always fought away from home - leaving Britain free to prosper in peace.
There are still a surprising number of determinist historians who think that being an island has somehow always guaranteed Britain against invasion, and that this has been easy and automatic. But they would perhaps do well to consider that England was successfully invaded by sea ten times between 1066 and 1688 - and that in reality it took the English a very long time to learn how to turn the sea to their own defence.
The determinists might also consider the history of Ireland, which illustrates what happens to an island that has never developed effective sea power. British seapower, by contrast, preserved the country from invasion and guaranteed peace and prosperity at home, up to the time of Trafalgar and beyond.
There is more to Trafalgar than this, however. Britain's command of the sea, in the face of Napoleon's Grand Army massing at Boulogne, was very far from secure in 1805, despite its successes of the preceding century. In three years as First Lord of the Admiralty, from 1801 to 1804, the megalomaniac Lord St Vincent had done as much as one man could to wreck British sea power. Obsessed with a nightmare vision of corruption which scarcely existed outside his own imagination, he had paralysed naval administration, emptied the storehouses, and dismissed a large fraction of the dockyard workforce. In 1804 his successor, Lord Melville, calculated that he had 81 ships of the line in commission, of which 18 were fit only for home waters, and none of the remainder had an estimated service life remaining of more than five years. When Spain entered the war, in December 1804, Napoleon had over 100 ships of the line available.
In the short term the British were able to hang on, thanks to the superior training of the ships' officers and men, but in the medium term Napoleon had an excellent prospect of winning command of the sea. The Royal Navy urgently needed a crushing victory to retrieve its position. There was not the slightest reason for Napoleon to offer it the opportunity, because by August 1805 the emperor's various invasion schemes had collapsed from the weight of their own absurdity, so completely that even he had noticed.
When he ordered his Combined Fleet to sea in October, his stated objective - to land a small force of troops in support of planned army operations in southern Italy, which formed a very minor part of his campaign plans against Austria - was so frivolous that it is hard to believe he meant it seriously. Recent French scholars have concluded that the order can only be explained in psychological terms, as the subconscious desire of wounded vanity to punish the hated navy for its failure to contribute to his glory.
After Napoleon's losses at Trafalgar, it seems to have taken him only a few months to realise what he had done. He spent the rest of his reign in a futile and immensely costly attempt to reconstruct his lost battle-fleet.
Without a battle-fleet Napoleon was condemned to an indirect strategy against his enemies, just as the British were. Britain, for want of a great army to commit to the European battlefield, could not win a decisive victory on land, but neither did she risk a decisive defeat. Similarly, Napoleon's defeat at Trafalgar made it impossible for him to intervene in the other decisive theatre of war, at sea.
Having thrown away his fleet, Napoleon had no direct means of attacking a maritime and commercial power such as that of Britain, and he was forced to resort to economic warfare. He believed in the orthodox French economics of his youth, according to which real wealth derived from land and people, while trade was essentially parasitic, and government borrowing was a system of fraud.
He thought a country like Britain, whose wealth derived from overseas trade and whose government waged war on credit, was nothing but a house of cards - which one good blow would bring down. In 1806 he imposed an economic blockade, known as the Continental System, which required his own trading subjects to sacrifice their livelihoods in order to wreck the British export economy. This did not concern him, as he had no opinion of the usefulness of merchants, especially as many of them were not even French.
The system did indeed damage the British economy, but it damaged European economies even more, and in the end it fatally undermined Napoleon's power. Everywhere in his empire merchants kept up their trade as much as they could, with the aid of bribery and false papers. His soldiers and officials, even at the highest levels, were eminently corruptible, so that behind the official façade the political glue of the regime was dissolving.
What was more, his strategy of economic warfare obliged Napoleon to attack every neutral European power that did not choose to participate in his system - but Portugal resisted, Spain rebelled, Sweden evaded his demands and Russia changed its mind. Thus the strategic logic of war against a naval power, without a fleet, drew French armies into campaigns that finally ruined them. Without Trafalgar none of this would have been necessary.
Moreover Napoleon's empire was never politically or economically stable. His revenues never covered the expense of government. To feed his armies, to endow the new military aristocracy which guarded his throne, he needed continual conquests. A lasting peace between France and her neighbours was impossible under his rule, or at least incompatible with his ambitions.
His enemies in continental Europe, who had the same interest in a balance of commercial and maritime power as the British had in the balance of power in Europe, desired to maintain France as a counterweight to Britain, and repeatedly (even as late as 1814) offered him terms that would have saved his throne and many of his conquests. He refused them all, however, and this in the end persuaded them that for their own survival they had to crush him, and force his consent to a peace treaty - the Congress of Vienna, 1815 - that secured Britain unchallenged naval supremacy. As the Prussian Field-Marshal August Gneisenau declared, in 1815:
'There is no mortal to whom Great Britain has greater obligations than this blackguard ... for it is the events which he has brought about which have raised England's greatness, security and wealth so high.'Condemned by his character and situation to constant aggression, Napoleon could only have escaped his fate by finding some means of expansion outside Europe, where Britain was more vulnerable and the continental great powers were less concerned. With naval power he might have done it - but at Trafalgar he lost that option. Without a battle-fleet he was shut in a strategic box from which there was no escape - he had thrown away the key.
After Trafalgar, there was still long and hard fighting to be done to bring home to the emperor that he had exhausted his long-term options. Most of this fighting was done by the armies, though in effect it was paid for by the Royal Navy, which safeguarded the overseas trade by which Britain earned its own livelihood and subsidised its allies. Just as in World War Two, sea power had to win its war first, if the country was to survive and the soldiers were to have their chance.
Trafalgar did more, however, than hold the ring at the worst crisis of the war. It won Britain an unchallenged command of the sea, in quantity and quality, materially and psychologically, over all her actual and potential enemies, which lasted long after the age of Napoleon.
The victory allowed 19th-century Britain to reduce the Navy well below its present size without running any serious risks. Beyond the fall of Napoleon, the achievement of Trafalgar was to settle Britain's security for a century.