Foreign policy is not something you can make up as you go along. The greatest statesmen - Bismarck, Salisbury, Churchill, Kissinger - all thought long and deeply about history before entering the realm of power. Unfortunately, like his nemesis, George W Bush, Tony Blair showed little interest in international affairs prior to reaching the top of the political greasy pole. It has shown.
In the 1983 general election, for example, Blair toed the Labour Party line of British withdrawal from the European Economic Community and unilateral nuclear disarmament. As Prime Minister, by contrast, he set out to be a more committed European than his two Conservative predecessors, while at the same time affirming his faith in the Atlantic alliance with the United States and renewing Britain's nuclear deterrent.
Superficially, this was a coherent foreign policy, even if it was largely improvised. In Timothy Garton Ash's phrase, Blair was attempting to be the "bridge" between the United States and Europe, while maintaining a degree of national autonomy. Yet the events of the past 10 years have revealed this bridge to be a very rickety edifice, rather like the shiny Millennium Bridge across the Thames, which was fine until people actually started walking across it.
It turns out that there are fundamental conflicts between our commitment to "ever closer" European integration, our supposedly "special relationship" with the US and our national self-interest. Far from having a grand design, to vary the metaphor, Blair has resembled a desperate superwoman in a glossy magazine, trying simultaneously to be a sex kitten, a chief executive and a domestic goddess. Alas, "having it all" is not an option in international relations.
It is easy to forget how eager Blair was to talk the European talk in the first four years of his premiership. The holidays in Tuscany set the scene. The public school French put his monoglot predecessors to shame. Yet Blair's belief in Europe was never much more than skin-deep. He evinced little regret when Gordon Brown rejected the possibility of British adoption of the euro. And when it came to the crunch in 2003, a choice between the US and the two dominant members of the EU, he unhesitatingly chose the former.
What was it that turned Tuscan Tony into Texan Tony? It is often assumed that it was September 11, 2001. At the Labour Party conference three weeks afterwards, Blair himself described 9/11 as "a turning point in history, where we confront the dangers of the future and assess the choices facing humankind". Yet the real turning point for Blair's foreign policy had in fact come earlier.
Twice before 9/11 he had witnessed and marvelled at the remarkable efficacy of Western military power: first in Serbia in 1999, then in Sierra Leone the following year. Short, sharp interventions in civil conflicts had spectacularly positive results. Serbia went from ethnic cleansing to elections. Sierra Leone went from decapitations to democracy.
In Blair's mind, then, the doctrine of liberal or humanitarian interventionism was fully formed a year before the shock of 9/11. The notion of the inviolable sovereignty of the nation state could be discarded, central though it had been to the international system from the Treaty of Westphalia to the United Nations charter. A state that engaged in genocide, or, by extension, terrorism, forfeited its rights. Thus, when 9/11 happened, no other leader was more ready to embrace an American policy of retaliation that meant violating the sovereignty of multiple nation states.
Blair's October 2001 speech was a remarkable call to arms, pledging not only to bring the Taliban regime to book for sheltering al-Qaeda, but also "to strike at international terrorism wherever it exists". In the early days of the Iraq war, Blair remarked to a journalist: "What amazes me is how many people are happy for Saddam to stay. They ask why we don't get rid of Mugabe, why not the Burmese lot? Yes, let's get rid of them all. I don't because I can't, but when you can, you should."
There is no need to determine here why exactly the Bush administration decided to make Saddam Hussein its next target after the overthrow of the Taliban. The point is that, with very little hesitation, Blair accepted the argument that the Iraqi dictator not only possessed weapons of mass destruction (and therefore posed a threat to the west) but was also a sponsor of terrorism.
When he addressed the Commons on March 18, 2003, Blair somehow managed to link the chemical and biological weapons the UN inspectors had not been able to trace in Iraq to the possibility of a terrorist attack comparable with 9/11. To Blair's critics in 2003, he had become America's "poodle"; a supplementary secretary of state. But a better description was that he had become the president's barrister, making the case for the prosecution of war in Iraq with all the rhetorical skills of a highly talented silk.
Having embarked on this course, however, Blair soon found his much-vaunted Atlantic bridge crumbling beneath him. The French and the Germans led European opposition to military action against Iraq, dashing any hope of a legitimating second resolution from the UN Security Council. Meanwhile, at home, there was dismay across the political spectrum.
From a British vantage point, the costs of backing the US were immediately obvious. But what were the benefits? One senior analyst at the State Department candidly described the relationship between Bush and Blair as "one-sided... There was nothing, no payback, no sense of reciprocity". That crudely condescending salutation "Yo, Blair" said it all.
What had once been a bridge looked suddenly like a forlorn jetty on America's Eastern seaboard. And Blair has been standing there ever since, feebly shadowing American policy, not only towards Iraq, but also towards Israel and the Palestinians, Iran and Lebanon. His last feeble attempt to breathe life into the European constitution revealed all too clearly the evaporation of his influence on the Continent.
In foreign policy it is often the idealists who do the most harm. Tony Blair's tragedy was that, though he was a hard-bitten realist in the realm of domestic politics - the man who led Britain's socialist party reluctantly back to capitalist economics and liberal politics - he was an ing'nue when it came to international relations, a beginner who drew a dangerously simplistic inference from two early successes.
The road to Baghdad led through Belgrade and Freetown; but it was a wrong turning. As a result, Blair will go down in history as one of those rare prime ministers, like Eden, Asquith, Gladstone and Aberdeen, who failed abroad rather than at home.