Following the publication of the Chilcot Report, the former prime minister said that the decision to remove Saddam Hussein was the “hardest, most momentous, most agonising” of his 10 years in office.
“For that decision I accept full responsibility, without exception, without excuse,” he told a news conference, his voice near breaking.
“For all of this I express more sorrow, regret and apology than you may ever know or can believe.”
Addressing the media in London shortly after the release of the report, Mr Blair said: “I recognise the division felt by many in our country over the war, and in particular I feel deeply and sincerely — in a way that no words can properly convey — the grief and suffering of those who lost ones they loved in Iraq, whether members of our armed forces, the armed forces of other nations or Iraqis.”
The former prime minister said he would never agree that those who died or were injured in Iraq “made their sacrifice in vain”.
“They fought in the defining global security struggle of the 21st century against the terrorism and violence which the world over destroys lives,” he said.
“Their sacrifice should always be remembered with thanksgiving and with honour when that struggle is won, as it will be.”
Mr Blair said he was aware that some families of the dead “cannot and do not accept this is so” and that “there are those who can never forget or forgive me for having taken this decision and who think that I took it dishonestly”.
But he said while the report contained criticisms, it showed “there were no lies, parliament and the cabinet were not misled, there was no secret commitment to war, intelligence was not falsified and the decision was made in good faith”.
Mr Blair said: “The intelligence assessments made at the time of going to war turned out to be wrong, the aftermath turned out to be more hostile, protracted and bloody than we ever imagined. The coalition planned for one set of ground facts and encountered another.
“And a nation whose people we wanted to set free and secure from the evil of Saddam became instead victim of sectarian terrorism.”
He said he “profoundly disagreed” with claims Saddam’s removal had caused the upsurge in terrorism in the Middle East.
He said: “Saddam was himself a wellspring of terror, a continuing threat to peace and to his own people.
"If he had been left in power in 2003, then I believe he would have once again threatened world peace and when the Arab revolutions of 2011 began, he would have clung to power with the same deadly consequences that we seen in the carnage in Syria today.
"At least in Iraq, for all its challenges, we have today a government that is elected, is recognised as internationally legitimate and is fighting terrorism with the support of the international community.”
He added: “The world was — and is — in my judgement a better place without Saddam Hussein.”
Mr Blair accepted the report made “serious criticisms of the way decisions were taken”, adding: “I accept full responsibility for these points of criticism, even when I do not fully agree with them.”
He insisted he did not commit Britain to war months before the invasion began with his note to US president George W Bush which declared “I will be with you, whatever”.
“There was no rush to war,” he said. “The inquiry rightly dismisses the conspiracy theory that I pledged Britain unequivocally to military action at Crawford, Texas, in April 2002.
Blair vowed support for Iraq action ‘whatever’
Tony Blair privately assured George Bush eight months before the invasion of Iraq that he would be with the US president “whatever” when it came to dealing with Saddam Hussein, the Chilcot Inquiry has disclosed.
In a six-page memorandum to Mr Bush, marked Secret Personal, Mr Blair argued that toppling the Iraqi dictator was “the right thing to do” and that the crucial issue was “not when, but how”.
The document, dated July 28, 2002, is among 29 letters and notes sent by Mr Blair to Mr Bush between 2001 and 2007 to be released by the inquiry.
In it, the British prime minister set out a strategy for presenting Saddam with an ultimatum demanding he admitted United Nations weapons inspectors back into Iraq in the expectation that he would “screw up”, providing a cause for war.
“I will be with you whatever. But this is the moment to assess bluntly the difficulties. The planning on this and the strategy are the toughest yet. This is not Kosovo. This is not Afghanistan. It is not even the Gulf War,” he wrote. Mr Blair frankly admitted that he could not be sure of support in Britain for his plan — even among members of his own government — while public opinion elsewhere in the world was likely to be strongly opposed.
“If we win quickly, everyone will be our friend. If we don’t and they haven’t been bound in beforehand, recriminations will start fast,” he wrote.
He went on: “And — and here is my real point — public opinion is public opinion. And opinion in the US is quite simply on a different planet from opinion here in Europe or in the Arab world.
“In Britain right now I couldn’t be sure of support from Parliament, Party, public or even some of the Cabinet. And this is Britain. In Europe generally, people just don’t have the same sense of urgency post 9/11 as people in the US.”
Mr Blair acknowledged that there would be “reluctance” in the US about taking the issue to the UN Security Council, but insisted it was the best way to provide them with a legitimate case for military action.
“We don’t want to be mucked around by Saddam over this, and the danger is he drags us into negotiation. But we need, as with Afghanistan and the ultimatum to the Taliban, to encapsulate our casus belli in some defining way,” he wrote.
“This is certainly the simplest. We could, in October, state that he must let the inspectors back in unconditionally and do so now, i.e. set a 7-day deadline.
“There would be no negotiation. There would be no new talks with (UN Secretary General Kofi) Annan. It would be take it or leave it.
“I know there will be reluctance on this. But it would neutralise opposition around the UN issue. If he did say yes, we continue the build-up and we send teams over and the moment he obstructs, we say: he’s back to his games.
“That’s it. In any event, he would probably screw it up and not meet the deadline, and if he came forward after the deadline, we would just refuse to deal.”
The prime minister emphasised the importance of presenting the evidence about Saddam’s supposed weapons of mass destruction (WMD) as well as trying to establish a link with al Qaida in the aftermath of the 9/11 attacks on the Twin Towers in New York the previous year — although none was ever found.
“If we recapitulate all the WMD evidence; add his attempts to secure nuclear capability; and, as seems possible, add on Al Qaida link, it will be hugely persuasive over here,” he wrote.