Nearly three years ago, the bicentenary of the battle of Trafalgar was marked in far-flung corners of the world and today marks the 250th birthday of the naval hero who conceived and executed it -- Horatio Nelson.

The battle, fought between the Royal Navy's 27 ships commanded by Nelson and the combined Franco-Spanish fleet of 33 ships under Admiral Pierre Villeneuve, led to the capture of 17 of Villeneuve's fleet and an 18th blown up, without loss of a single British ship. It was the greatest naval victory in the annals and was additionally touched with pathos -- Nelson was mortally wounded by a French sniper at the height of the battle. But why is a faraway sea battle fought by Europeans two centuries ago of any interest today?

First, a resonant historical context: Trafalgar came at the end of a two-year invasion threat to England posed by a Napoleonic France busy subduing the European continent. British Prime Minister William Pitt, like Winston Churchill 135 years later, had the Herculean labor of keeping Britain secure and working assiduously to open new fronts against the Continental dictator even as allies succumbed to his onslaught. A somewhat different but equally daunting challenge, in a world rendered vastly more imperiled by the advances of technology, will soon devolve upon the next incumbent of the White House. Like Pitt and Churchill, the next president will also have to deploy forces around the world to meet a transnational Islamist challenge, often without the benefit of stable or reliable allies.

Second, brilliant, unorthodox tactics: With Nelson, the age of fleets massing in parallel columns and exchanging broadsides gave way to riskier yet more rewarding tactics. Nelson ordered a frontal attack by his fleet in two columns to break the Franco-Spanish battle line. The aim was to overwhelm Villeneuve's center and rear before his vanguard ships could turn and come to his aid. It was classic instance of deploying scarce resources in concentration at the point where they can be devastatingly effective. Today, when conventional mass clashes are becoming the exception rather than the rule in warfare, numbers count (witness the surge in Iraq) but important above all are bold, unconventional strategies (General Petraeus' innovative use of counter-insurgency doctrine, for example) for atomizing, disorienting, and defeating opponents.

Third, the power of a magnetic commander who is neither a dictator nor acting on behalf of one: Courage, devotion to duty, and tenacity aside, Nelson did not fit the traditional mould. He never overcame seasickness and was almost feminine in his emotions, and his tactical brilliance was matched by utter devotion to his officers and men, who returned an exceptional affection. But Nelsons come but once in a run of centuries and it is no disparagement of today's intrepid officers to say that we must make do without one.

Fourth, the most vital factor -- values: Britain's victory at Trafalgar is the expression of a motif that resonates today -- to commit forces to the containment and defeat of transnational threats. Once it was the job of the Royal Navy to keep the sea lanes free, extirpate piracy on the high seas, end the slave trade on water, and contain dictators. Today keeping the peace and eliminating global threats falls heavily upon the U.S. armed forces. It must, however, also fall increasingly on a network of like-minded allies.

In a world of politically centralizing, bureaucratic tendencies, a vigorously sovereign, free market, democratic alliance composed primarily of countries of British norms and traditions -- dubbed the "Anglosphere" by James C. Bennett -- might yet prove a corrective. Neither economically, ethnically, nor geographically unified, such an alliance can supply a unified response sorely lacking in international institutions like the United Nations, which are beholden to politics of the lowest common denominator and composed of governments (mostly repressive and unrepresentative), not peoples.

The importance of that alliance will be found not only on land but, increasingly, at sea. Naval power itself, seemingly eclipsed in significance by air forces, ballistic missiles, and nuclear weapons, remains as important as ever. Aircraft carrier battle groups enable worldwide deployment and rapid redeployment of combat forces backed by sea and air power and obviate the complication of a ground presence in lands that are militarily unstable and politically Byzantine.

For these reasons, the aircraft carrier is likely to prove more rather than less vital in the years ahead. Yet the U.S. Navy is simultaneously over-stretched in commitments and contracting in size: the 15 carrier battle groups of the 1970s and 1980s have been left to dwindle to just 11 currently on active service and, on current estimates, may dwindle to 10 by 2012.

That is one reason why -- in the absence of a Nelson and a dispositive triumph of a Trafalgar -- the navies of other democracies (Britain, India, Australia, to name three) will become increasingly important. Let us hope America's allies step up to the plate.