Cast your mind back to the Labour conference of 1997. Tony Blair had been given two nicknames by a party that held him in awe and affection - Kim Il Sung and Bambi. The new Prime Minister assured the faithful he was neither of the above. He was a regular guy whose policies were determined by the need to do the right thing. He was not a narrow ideologue, he was a pragmatist - but his actions were guided by a firm moral compass. This moral compass has taken him to Iraq, Kosovo, Sierra Leone, Afghanistan and now back to Iraq.
What is it about this Islington family man who used to take his kids on Saturday morning to swimming lessons, that he needs to commit British forces to military action for the fifth time in as many years? No prime minister in modern times comes close to that record.
As mission co-pilot, Blair is locked on to a target. On one level he is comfortable. He wants to rid Saddam Hussein of his weapons of mass destruction and believes that time has all but run out to do it peacefully. He believes Britain has no choice but to be America's closest friend and ally, and is prepared to subjugate most other considerations to achieve that end.
And yet, on another level, he is alarmed. This is not where he wants to be. Mocked by a TV audience as "Mr Vice-President", increasingly unpopular in the polls, Blair knows he has singularly failed to get his message across of the need for war. These next few days will be crucial for the conflict in Iraq and personally for him. He is desperate for a second UN resolution - any will do - giving a fresh mandate for action against Iraq and taking some of the edge off public hostility to war. George Bush now says he doesn't mind having one, but is not prepared to let the UN inspectors hang around and let the French, Germans and Russians tie his hands. But the moment Blair hoped would never come may fast be approaching: when he is forced to commit himself to a war that the UN hasn't sanctioned, that much of Europe resists and that his party and people do not want.
How has he got himself into this position?
Before he came to power, Blair displayed very little interest in foreign affairs. In the heady first few months of government, the only foreign policy issue that exercised him was the UK's place in the European Union. Blair was happy to subscribe to a Foreign Office orthodoxy: the need to maintain and bolster a special relationship with the United States. As early as 1998, he proved his credentials by supporting brief campaigns of bombing on Afghanistan and Sudan, against a world opinion that saw both actions as nothing more than an attempt to distract attention from Bill Clinton's embroilment in the Monica Lewinsky affair. Four months later came a dress rehearsal for the current crisis with Iraq. Saddam Hussein had thrown out the UN inspectors and Blair lined up behind Operation Desert Fox, another US aerial bombardment, despatching a token force from the RAF.
Those events showed one side of the Blair world-view: you pick your friends and you stand by them.
Blair's next two wars, Kosovo and Sierra Leone, show the other side of Blair - the Gladstonian intervener. Kosovo saw Nato overcoming after considerable argument the old, cold war mentality of strategic compromise and non-interference. Sierra Leone provided a different lesson for him: the limits of international engagement, and the failure of the UN to meet its obligations, leading the former colonial power, the UK, to send in troops for a humanitarian purpose - to get rid of a very bad regime and replace it with a less bad one. "When people say: 'Run an ethical foreign policy,' I say Sierra Leone was an example of that," Blair once said.
By mid-2000 Blair was at the pinnacle of his international powers. He was at the heart of European decision-making, his enthusiasm contrasting with weak governments in France and Germany. All around were centre-left administrations that looked to him for inspiration. As Clinton prepared to leave power, he came to London to urge Blair to get in with the president-elect (or not really elect), George W Bush.
Clinton gave his advice just over two years ago. It is something that has guided Blair ever since. It influenced his reaction to the events of 11 September and his role in the subsequent war in Afghanistan and the "war on terror". It dictates his policy now towards Iraq. Blair believes Britain derives what authority it has in the world through its closeness to the US. Through it, and through it alone, we exercise a certain influence.
And what of the other side of Blair, the convinced multi-lateralist, the committed intervener? "We are witnessing the beginnings of a new doctrine of international community," Blair proclaimed in his speech in Chicago in April 1999, his own foreign policy mission statement. Blair set out tangible and credible benchmarks for global action, saying: "We are all internationalists now, whether we like it or not."
That was before the birth of the new world order and the new doctrine of pre-emptive attack conjured by Messrs Rumsfeld and Cheney. And yet, in conversations with me, Blair's people remain convinced that they can marry the liberal interventionism of the late 1990s with the darker realities of global terrorism and Bush.
That is where Iraq comes in. And that is why Blair is at least as committed to military action as his ally in the White House. For Bush and the hawks, this war is about completing unfinished business and establishing a bridgehead of American values in a fundamentally hostile region. When Bush said in his State of the Union address last month that different problems required different solutions, he was distancing himself from his "axis of evil" speech the previous year, which appeared to presage an era of perpetual American military intervention. Even if the Iraqi war is successful in a narrow military sense - few allied casualties, an "acceptable" level of Iraqi deaths (whatever that means) and a speedy conclusion - Bush is likely to revert to his pre-9/11 persona. Nation-building and interventionism go against the grain.
For Blair, Iraq is about something else, something bigger. He will want to capitalise on it to "deal with" other transgressors, hence his alarmist recent reference to North Korea in the Commons. More vital to the Blair world-view, however, will be the need to demonstrate to the party and the British public a more "positive" agenda, post-Iraq.
Top of the list is a new engagement with the Israelis, and that is one of the reasons Blair looked so glum on his return from his talks with Bush in Washington on 1 February. The British government is getting nowhere with trying to influence the Americans to put the squeeze on Ariel Sharon. Blair knows that his honourable failure on this issue reinforces the view of a sceptical public in Britain that sees his relationship with Bush as one-way.
Credibility is Blair's biggest problem. He needs to show that he influences the US, but cannot trumpet it, which leads many to doubt that he has it. He needs to show that when he gets passionate about tackling poverty from "the slums of Gaza to the mountains of Afghanistan", he really means it and he really can do something about it. He needs to demonstrate that when he worries about Saddam's human rights record, he is equally exercised by the records of others.
After the debacle of its PhD dossier, the Blair spin machine might have enjoyed some moments of light relief, seeing the tabloids denounce the treachery of the French and Germans. But the wiser heads around the PM know that the redrawing of the map of Europe into "old" and "new" is a figment of Donald Rumsfeld's imagination. Once the Americans withdraw and leave peacemaking in a shattered Iraq to the rest of the international community, Europe will be required to work together again.
As for Blair himself, a "good" war will leave him feeling vindicated. But his people know that the glow of victory will not last long. Nobody doubts that, as the world's only superpower, the US should be able to win any war against a country such as Iraq with ease. And nobody doubts that when the next foe appears on America's radar screen, Blair will be there, with Britain's smaller forces, as ever, at the ready.
John Kampfner's new book, Blair's Wars, will be published by Simon and Schuster in the autumn