John Kampfner: And still no one has been held to account for Iraq

The prime minister chose to fight four wars in his first five years in office

One picture sticks in my mind about Tony Blair in the weeks leading up to the Iraq invasion. The man who would send British soldiers to their deaths for a war of dubious legality would saunter upstairs to the family apartment whenever he could of an evening to play air guitar with his children.

The many people I spoke to during my research for Blair's Wars spoke of his supreme confidence, his almost chilling serenity, at this moment of utmost responsibility. They spoke of him at the time with awe.

This will not be one of the areas to be pursued by the Chilcot enquiry as it questions its star witness tomorrow. For the past two months the panel has chivvied away, asking the great and the good – military chiefs, mandarins and ministers – ever so gently about the actions they took and didn't take.

As Chilcot said from the outset, nobody was being put on trial. That is the way the system works. The approach of his team has been invariably mild, occasionally caustic, but studiedly respectful. Many of the witnesses have used their moment in the limelight to settle scores or to write their own version of history, in the hope of wiping some of the stain off their own records.

It was too much to ask of the enquiry to come up with a smoking gun, that one single piece of information that would change the story of the most ignominious foreign policy adventure of modern times. Yet it has eked out some fresh information that will be intriguing for historians and political scientists.

We now know beyond reasonable doubt, for example, that Blair committed himself to joining George W Bush in military action to topple Saddam Hussein when the US President hosted his best buddy at his ranch in Crawford, Texas, in April 2002. I revealed this in Blair's Wars. Documents written by Blair's foreign policy adviser, Sir David Manning, subsequently corroborated it.

The enquiry has confirmed it through the former Ambassador to Washington, Sir Christopher Meyer. Alastair Campbell, in testimony that provided rich pickings for psychoanalysts, admitted that in a series of private letters between the two leaders in 2002 Blair told Bush that if "it is to be done militarily, Britain will be there".

The enquiry has also shed more light on the dodgy legal advice. This week, the testimony of the top two lawyers at the Foreign Office vividly demonstrated Jack Straw's disdain for propriety. They showed the extent to which the Attorney General, Lord Goldsmith, did what was required of him and re-tuned his brain to delete his concerns about the legality of war.

These individual stories add texture to the narrative. They show the obsequiousness and spinelessness of virtually all the main figures who saw their mission as to do their boss's bidding. Apart from the late Robin Cook and the deputy foreign office legal adviser, Elizabeth Wilmshurst – who left the enquiry on Tuesday to unprecedented applause – barely a single person resigned in protest in 2002-03.

Yet, in order properly to understand Blair, the enquiry team and the wider public need to step back from the immediate detail. They need to understand how one prime minister chose to fight four wars in his first five years of office – Operation Desert Fox in 1998, Kosovo in 1999, Sierra Leone in 2000, Afghanistan, and then Iraq.

They would be wise to recall how in May 1999 Blair visited Aachen, on Germany's western border, to receive a prize as the world's most respected international statesman of that year. The award is named after Charlemagne, the first Western emperor, and it was particularly poignant that it had been given to a man who had come to see himself in that role.

Two years later, after the events of 9/11, Blair luxuriated in the ovation he received from Congress for the "support" he had rendered in America's darkest hour. He was rewarded with the unofficial title of Bush's special emissary, tasked with winning round recalcitrant figures such Vladimir Putin of Russia and General Pervez Musharraf to supporting Bush's invasion of Afghanistan and the "war on terror". Blair was in his element.

Yet his loyalty was sorely tested only months later in January 2002 by Bush's state of the union speech in which he highlighted his "axis of evil" – North Korea, Iran and Iraq. Blair's people were shocked that they had not been informed in advance. The prime minister ordered them to scurry to catch up with the White House, to do whatever it took to show that the "special relationship" was alive.

Blair's approach was one of hubris but also under-confidence about Britain's role in the world. He believed that the UK's place in the world was defined by our proximity to whatever administration was in office in Washington. This was standard Whitehall practice, but Blair took it to a logical extreme.

From Crawford, for a full year ahead of the war, Blair was locked into a fixed position, like a fighter jet locked onto a target. The casus belli – regime change or weapons of mass destruction – was a detail to be overcome; he had promised Bush he would stand by him, come what may. This was his mission. A prime minister lightly read and little-versed in the complexities of Middle East politics and history had little reason for self-doubt. The task of his lawyers, ministers and defence planners was to deliver for him.

Tomorrow's appearance will produce some box-office moments. Blair will apply his usual mix of chat-show charm and steeliness, repeating his narcissistic mantra that he did what he thought was right. Perhaps he will inject a soupcon of regret for the odd detail. He will then waft away.

One man bears supreme responsibility for this most ignominious chapter in British foreign policy and political life. But many others played their part too, with their sins of omission and commission. Not one, not a single person, has been held to account, least of all Blair. He got away with it a long time ago. He always knew he would.

John Kampfner is author of 'Blair's Wars' and 'Freedom For Sale'