‘I will be with you, whatever.” These words, in a personal memo from Tony Blair to George W. Bush on July 28, 2002, are said to condemn Blair. Just six words out of John Chilcot’s 2.6 million frame the indictment. They show, say Blair’s critics, that he was irrevocably committed to war. Some even claim the words prove that Blair was “lying” in all his subsequent public statements about Iraq before the coalition invaded it on March 18 the following year.

These accusations misunderstand, sometimes wilfully, how government and diplomacy work. The leaders of allied powers rightly seek friendly relations with one another. In the case of America, by far Britain’s most important ally, the British take particular trouble to do so. This matters the more if — as was true of Bush and Blair — the leaders in question come from different parts of the political spectrum: the need to build trust is greater. After 9/11, Blair saw quicker than any other world leader how what he called “the kaleidoscope” had shifted. He got closer to the president than did any other ally. He wanted to help shape the response to Islamist terrorism. He joined Britain with the US-led expedition against the Taliban in Afghanistan. He won the Americans’ trust. He came to agree with Bush’s assessment of the threat posed by Saddam Hussain. In consequence, he was listened to by the Americans.

The two men considered themselves friends. Friends say things to encourage one another — “I’m right behind you”, “I will be with you, whatever”. When the leaders of democracies are friends, they don’t forget politics. Both sides know that these intimate exchanges will always be qualified by law, governmental process, parliamentary or party disagreements back home, by-elections, opinion polls and the ever-present possibility that the national interests of each will be forced by events to diverge. Both understand that their assurances are not secret, legally binding oaths about future action. They are strong and sincere expressions of friendly intent. So when Margaret Thatcher wrote to her great friend Ronald Reagan during the Iran-Contra scandal in 1986 and said: “anything which weakens you, weakens America, and anything that weakens America weakens the whole world”, she was not saying Reagan was right to have done his secret deal with Iran, or that Britain would support every US policy. She was saying: “Our alliance matters most” or — though she didn’t do demotic — “I will be with you, whatever.”Blair was not telling Bush — and Bush did not think he was telling him — “I’m going to invade Iraq with you, come what may.”

His very next sentence in the memo “bluntly” raised “the difficulties”. He was telling him that he shared his aim, and intended to support him. It is usually a mark of good leadership to forge a close bond with a great ally for a big purpose: it is certainly not a lie or a crime.

Chilcot and his team have worked for many years to set out calmly, with full evidence, what most people half-knew already about the war in Iraq. We learn that the Blair government did not follow proper Cabinet and government process; that the secret services did not include enough caveats about their intelligence (and that the government did not interrogate it properly); that the military were over-optimistic about what they could do, and inadequately equipped; that the aftermath of the (successful) invasion was not planned for, with shocking results.

And, of course that — as he almost always does — Blair exaggerated and skated on thin ice to get what he wanted. The report contains lesson after lesson, not just about the man in charge, but about how our government, Cabinet, law officers, spies, generals etc should work. So perhaps it was worth the wait But the wrong lessons will have been learnt if we now come to believe any of the following: that Britain should never fight an expeditionary war; that Britain should not be the ally of the United States; that British soldiers’ lives must never be lost (or even that each loss has to be individually justified); that the views of dead soldiers’ families must be the guide to policy; that the run-up to any war must be disclosed in full to Parliament at the time; that private communications with allies can be made public without damage to alliances; that lawyers should not just advise, but decide; and that political leaders, if things go wrong, should be treated like murderers.

The argument for Tony Blair is not that he got it right, but that he made the decisions which a prime minister is entitled to make. Indeed, his case is a bit stronger — that he understood, better than most leaders nowadays, what the important decisions were. In judging him, one should remember how narrow in war can be the margin between victory and defeat. Thatcher, for example, is remembered for an astonishing victory in the Falklands war. If she had lost just one aircraft carrier, the result might have been defeat. Would it have been right, if that had happened, to have pilloried her for the rest of her life?Blair understood that a decision has consequences either way. It is what he calls “binary”, and it has a “counterfactual”.

He thought that the two key decisions were “Is the world better off without Saddam Hussain?” and “Were we with America, or not with America?” It would be a bold person — there are lots of startlingly bold people around just now — who could confidently say that there was no case for the Blair answer to either question. That is why he says, with a restraint for which he gets too little credit, that his critics would do better to disagree with him than brand him “deluded”.

He confronted the real difficulties of such decisions: they never have. Compare Blair to a previously successful heart surgeon who risked a big operation to save a life, but failed. What sort of a culture is it that tries to rip apart such a person? Does such behaviour encourage better heart surgery in future, or a retreat into timidity? Distressed parents of dead servicemen, exploited by the media, are led to think that their sons’ deaths should be laid at the door of a prime minister. We do not hear from the many stoical parents who know that a man (or woman), by joining the Army, accepts the possibility of death, and who take comfort in the professionalism of the one they have loved and lost. There is a counterfactual not just about Blair’s — and Bush’s — decisions then, but about our attitudes towards those decisions. Those attitudes will affect our role in the world, and the state of that world. Indeed, they already have.

The blood-drenched anarchy of Syria, years long, is what happens when Western powers give up. So is the consequent flood of refugees which is changing politics across Europe.Tony Blair sought a global strategy for Britain, but mismanaged too much of it. Now we can either try to build a better one, or have none at all. It’s a binary choice — one on which the next British prime minister (whichever she is) needs to pronounce before she is chosen.

— The Telegraph Group Limited, London 2016

Charles Moore is an English journalist and a former editor of the Telegraph.