Now that Sir John Chilcot's report has landed with a shuddering crash, how are we to judge Tony Blair, at the centre of it all?

The criticisms in Sir John's two and half million words are widespread and damning. He charges Mr Blair with leading Britain into a war of choice in which peaceful options had not been exhausted, with devastating results.

And so much more: keeping legal advice from the cabinet; overstating the certainty of intelligence; dispensing with Cabinet committees; committing to the use of force without cabinet discussion; too easily following the US lead; failing to ensure proper preparations for occupation; overstretching the military.

The report lays bare the failures in excruciating detail.

The thrust of Mr Blair's defence, delivered in breaking voice after the report's publication, was that he did what he thought was right, acting in good faith. He wishes us to judge him not only on what he did, which Chilcot does forensically, but on his motivations.

Is there something that should command our attention in all this and perhaps lead to a more complex judgement? How did Tony Blair find himself in this position: using all his tenacity and political skill to bend both government and parliament to follow him in something he believed unwaveringly was right, but which went so horribly wrong?

Mr Blair is rightly the overwhelming focus of our attention. Why? Because in his second term, his domestic political dominance and control of the machinery of government meant that key foreign policy analysis and decision making was happening, in the final analysis, in the soft grey matter within his head.

This indeed is one of Chilcot's main criticisms: that things ought not to be done this way.

Tony Blair's written memo to President Bush in July 2002, opening with the now infamous words, "I will be with you, whatever," as Chilcot has it, "had not been discussed or agreed with his colleagues."

Once Mr Blair had reached his own conclusions, he sought to drive them through. In believing Saddam posed a WMD risk, the government was a victim of group-think. In its overall policy approach, it was a victim of Blair-think.

So what did Mr Blair think? The rather clinical tone of the Chilcot Report stops somewhat short in analysing the personalities and world views that drove the central character. Here we have to colour the picture ourselves, and Sir John has delivered a goldmine in primary sources - not least private memos from Blair to Bush - to add to the existing record of speeches, interviews, memoirs and documents.

Whilst Chilcot places the critical decision making period between April and July 2002, in important respects the die was cast in Tony Blair's mind in the hours and days after 9/11.

That moment when America's clear blue skies were pierced by flame and twisted steel was for most of the world a moment of crisis, even panic. Not so for Mr Blair. It was not only, as the report notes, that 9/11 "changed perceptions about the severity and likelihood of the threat". Alongside Mr Blair's perception of threat there was also a perception of opportunity.

Long before being appointed to the inquiry, Sir Lawrence Freedman - an informal advisor to Mr Blair as Prime Minister - shared with me his impressions of the mood around the PM in the days after 9/11. In Number 10 he encountered neither panic nor foreboding but, rather, high excitement. For Tony Blair and his chief of staff, Jonathan Powell, 9/11 was "a great opportunity in international relations as well as a terrible tragedy, because everything is churned upside down and you can be creative in ways that you couldn't be creative up to now."

That mood was captured by Mr Blair's Labour conference address in October 2001, a speech infused with his activist spirit and reflecting the monumental scale of his personal ambition, as well as his view of Britain's role in the world and his perception of the difference that 9/11 had made. It was, as Prof Freedman described it to me, the "pure milk of Blairism." At its height, Blair proclaimed: "The Kaleidoscope has been shaken. The pieces are in flux. Soon they will settle again. Before they do, let us re-order this world around us."

Based on his vision and self-possession, Tony Blair assigned himself a global diplomatic mission to unite the world in a coherent response to terror. In the first 60 days after the crisis, Blair held 59 meetings and 34 phone calls with world leaders.

What was it that he believed had changed? On the one hand, the sense of threat. But also, and no less importantly, US attitudes. George W. Bush was transformed overnight from a president barely interested in global affairs to a doctrinal president with an "axis of evil" in his sights - and a zeal for sounding the bell of freedom in far-off lands.

Mr Blair's intent was not to be dragged in the wake of the roused beast but to harness its power for the job at hand: re-ordering the world.

Re-ordering the world? Yes, the former Prime Minister really believed that with the US engaged, the world could be transformed. And he cast himself and Britain in a key supporting role.

Naivity? Egomania? Messianism? It may seem so today. But for Tony Blair in 2001, after four years in power, and two landslide victories almost unthinkable today, there seemed to be no limits. Not only had he made peace in Northern Ireland, but he had saved the Kosovo Albanians from Molosovic - and faced down rebels in Sierra Leone.

Kosovo was particularly important for him. He had dragged a reluctant President Clinton into the fight and won the day, significantly, without the safety net of a UN Security Council resolution. Visit Kosovo today and you can meet 17 year-olds named Tonibler in his honour.

Kosovo led him, in a defining speech in April 1999, to lay out his "doctrine of the international community", an approach to world affairs that qualified the principle of non-intervention with a double argument.

First, it was morally right to confront a state oppressing its own population. Second, in a world where local conflicts have global ramifications, intervention was sometimes necessary. The global promotion of liberty, democracy and human rights were in the national interest.

The same speech alluded to Mr Blair's vision of Britain's historic role as the bridge between the United States, whose hard power was indispensable for securing liberty, and Europe, the model for free trade and interdependence.

Further emboldened by early success in dislodging the Taliban in Afghanistan, the Tony Blair that led the country down the road to war in 2002 felt that he was on a roll.

But why Iraq and why then? The threat of WMD was not a cooked up pretext. Mr Blair believed there was a threat because his intelligence chiefs believed it. So did CIA Director George Tenet, who infamously told President Bush that the case was "slam dunk", even gesturing with his hands to show the ball going through the hoop. Only later did Mr Tenet accept they were the "two dumbest words I ever said."

Yet it is also clear that Blair's ambitions were bigger. His vision for Britain's place in the world, side by side with the United States in the promotion of democracy and liberty, was coupled with a second vision. He was convinced that the Middle East could be transformed - indeed was ripe for change - and that the sting of radical Islam could be drawn by bringing about political reform, including regime change in Iraq, whilst resolving the Israeli-Palestinian conflict.

In his July 2002 memo to President Bush, Mr Blair declared: "Getting rid of Saddam is the right thing to do", not only because "he is a potential threat", but because "His departure would free up the region." And in another private memo shortly after the invasion he began: "Our fundamental goal is to spread the values of freedom, democracy, tolerance and the rule of law, but we need a broad based agenda capable of unifying the world to get it. That's why, though Iraq's WMD is the immediate justification for action, ridding Iraq of Saddam is the real prize."

So where did the Israeli-Palestinian conflict come into this?

It was not that Mr Blair believed Israel's actions caused Al Qaeda's anti-Western Jihad, as some of the Labour left did, but because he believed it was the lever which steered Arab and wider Muslim opinion. It was, he said in the July 2002 memo, "essential" because, for the Arabs, "this is the very soul of their attitudes."

Resolving it, or at least attempting to, would undermine Al Qaeda's propaganda, cool Arab opinion towards the West, and make it easier for Arab states to get on board. It would also help manage the left of his own party, for whom the Palestinian issue had an outsized significance.

Tony Blair bent President Bush's ear on "MEPP" (Middle East Peace Process) so often that he would apologise in his memos for being a "bore" on the subject.

Indeed he is still hammering away at Israeli-Palestinian peace now, running a self-starter peace mission in Jerusalem, even after stepping aside as Quartet envoy.

But back in 2002 and 2003 it was part of a wider Blair agenda: to pursue regime change in Iraq in a way that would bring the wider international community on board. In 2002 the notion spread through Whitehall that progress on the peace process was a condition for supporting the US on Iraq. Yet Mr Blair, and almost everyone else, was impossibly vague about what progress on the Israeli-Palestinian actually meant in the context of the raging Second Intifada.

It was also not his style to lay down concrete conditions or ultimatums for President Bush. He tried to persuade and to cajole, using his "shoulder to shoulder" commitments to open the door.

The Chilcot Report does not provide President Bush's side of the exchanges between them, but criticises Mr Blair for overestimating his influence. Other sources give the impression that, too often, his proposals were blown away in a George Bush whirlwind of flattery, chumminess and worthless reassurances.

Mr Blair did persuade the US to go down the UN route and did secure, belatedly, the publication of the Roadmap for a two-state solution. But it was a woolly framework which Israelis and Palestinian both failed to implement. The US showed little commitment to Israeli-Palestinian peace before Condoleezza Rice came to the view in President Bush's second term that it mattered.

Ultimately, Tony Blair believed in regime change in Iraq, even if progress on Israel-Palestine was out of reach. But his view that Iraq could be liberated by Western troops was, we now know, stratospherically naïve.

Viewed from this perspective, Tony Blair's principal deception was not of his cabinet and parliamentary colleagues, or even the public. It was of himself.

His sin, in a word, was hubris: an overinflated misperception of his ability to shape international politics, as he had so effectively shaped British politics. He is not primarily responsible for the invasion of Iraq or its dreadful consequences. The US would have gone in any case. But he must shoulder responsibility for Britain's part in it and his own hubristic global ambition.

Yet this judgement must come with qualifications. The documents released by Chilcot are a reminder that policy making is not done by machines, processing data and spitting out optimal choices like chess playing computers. It is done by human beings. Weighed down with mental limitations, biases and misperceptions, they must still make decisions.

Frequently they reach junctures where not acting presents as many risks as the various choices for action. There are always a thousand reasons for not doing something and officials in the corner asking 'are-you-sure-that's-wise-Prime-Minister?'. That's their job. But they don't have to answer for the consequences of action or of inaction.

Such moments demand leadership. Tony Blair wrote in his final written submission to Chilcot: "In the end there was a decision that had to be made: on the basis of the information available, to decide whether to join the US coalition and remove Saddam; or to stay out. I decided we should be in. The job of the Prime Minister is to make such decisions based on what he believes is in the interests of the country."

A government machine and the society it serves seeks such certainty. The public, and especially the media, punish equivocation and wavering. This kind of clarity, valued as leadership strength, can also go along with cognitive biases: seeking out information that reinforces the approach being pursued, filtering out dissonant voices or facts.

If it turns bad, as in Iraq, the decision maker bears the responsibility. But who is more to be condemned for the decision: the one at the top who took responsibility or all those who sheltered under their umbrella, whatever their own misgivings, because they knew someone else would carry the can? Only Robin Cook resigned his cabinet post over the decision to invade Iraq.

Where would we be without such individuals? Would Baroness Thatcher have sent the task force to liberate the Falklands? Would Sir Winston Churchill have committed to fight on against Adolf Hitler? Would Yitzhak Rabin have sent the IDF to Entebbe?

And would Tony Blair have declared on Kosovo: "Success is the only exit strategy I am prepared to consider?"

Most people cannot contemplate having to make such a decision. The self-assurance required is an abnormal trait. The pressure would crush most people. Such capacity is rare. We feel it now, at a time when Britain faces its greatest crisis in a generation, and a yawning chasm has opened up where its leadership and direction should be.

In the last few weeks we have seen David Cameron fail to unite the country behind his vision for Britain's future. We have seen Boris Johnson shrivel when faced with the consequences of his actions. It is hard not to recall that in 2005 Tony Blair won a Commons majority David Cameron would have given his teeth for, two years after the invasion of Iraq.

And for good or ill we see receding before our eyes the vision of Britain that Tony Blair believed in as the bridge between the US and Europe; the force for good in the world; the promoter of liberty and human rights; the embracer of intervention as enlightened self-interest.

We see the rise of an isolationist Britain, trying to turn back the tide of globalization and interdependence. And we see the same US that Tony Blair encouraged to engage in the world retrenching under President Obama, and flirting with the xenophobic bluster of Donald Trump.

Perhaps Tony Blair, too, carries some responsibility for the loss of faith in political leadership. But for all the misjudgements and mismanagement Sir John Chilcot exposes, we may yet miss the leadership and ambition that Mr Blair embodied, and the vision of Britain for which he stood.

Dr. Toby Greene is a Senior Goldman Fellow in the Hartog School of Government at Tel Aviv University and a Senior Research Associate for BICOM. He is author of Blair, Labour & Palestine: Conflicting Views on Middle East Peace After 9/11