The long-awaited official inquiry report into Britain's bitterly contested invasion of Iraq will finally be published today amid calls for Tony Blair to be held to account for taking the country to war.
Thirteen years after British troops crossed into Iraq and seven years after the inquiry began work, Sir John Chilcot will deliver his verdict on the UK's most controversial military engagement of the post war era.
The former Whitehall mandarin has said from the outset he would not rule on whether the invasion in 2003 was legal in terms of international law, pledging to provide a "full and insightful" account of the decision-making process.
But that is unlikely to quell the clamour for some form of legal action against the former prime minister if – as many expect – he is strongly criticised by Sir John and his inquiry panel.
With some families of the British personnel killed and injured in the conflict already dismissing the report as a "whitewash", Sir John insisted they had not shied away from criticism where it was justified.
"I made very clear right at the start of the inquiry that if we came across decisions or behaviour which deserved criticism then we wouldn't shy away from making it," he said in a pooled broadcast interview.
"And indeed, there have been more than a few instances where we are bound to do that. But we shall do it on a base of a rigorous analysis of the evidence that supports that finding."
The prosecutor at the International Criminal Court, Fatou Bensouda, has already made clear that charges cannot be brought in relation to the decision to go to war as the court has no jurisdiction over the "crime of aggression".
However General Sir Michael Rose, who commanded British troops in Bosnia in the 1990s and has been advising the families of some of the British dead and injured, said they were preparing to launch a civil action against Mr Blair.
"He has a personal responsibility as leader of this country to properly assess the intelligence and information that he is using to justify going to war," he told BBC Radio 4's The World at One.
"The consequences of that war have been utterly catastrophic. The families want to see justice and if it proves as a result of reading the report that there was dereliction of duty, malfeasance in public office, intelligence was negligently handled, then they will take action."
Sir John acknowledged the frustration at the time taken to complete the report but said they had faced a "huge task" in sifting through the tens of thousands of official documents as well as taking oral evidence from dozens of politicians, generals, diplomats and spies.
He had originally hoped it would be ready within two years of starting work in 2009, but it has since been hit by a series of delays.
The most serious has been bitter wrangling between the inquiry and the Cabinet Office over the de-classification of hundreds of official documents – most notably communications between Mr Blair and US president George Bush.
In May 2014 it was finally announced an agreement had been reached between Sir John and Cabinet Secretary Sir Jeremy Heywood that "gists or quotes" from the correspondence could be published, although Mr Bush's views would not be reflected.
That was followed by a further period of delay while the inquiry carried out the so-called Maxwellisation process – allowing individuals facing criticism the chance to respond before the report was finalised.
With the final report running to 12 volumes plus summary with 2.6 million words, much of the focus will be on the section dealing with the decision to go to war.
The inquiry heard evidence that Mr Blair and Mr Bush reached an agreement "signed in blood" they would topple Iraq dictator Saddam Hussein when they met at the president's ranch in Crawford, Texas, a year before the invasion – a claim Mr Blair denied.
However issues covered by the report run far wider – from the diplomatic build-up to the invasion following the 9/11 attacks on the Twin Towers in 2001 through to the end of the UK occupation in 2009.
They include the intelligence on Saddam's supposed weapons of mass destruction – the original justification for military action – and the legal advice of attorney general Lord Goldsmith, who finally gave the green light just days before the invasion, having previously warned that further authorisation from the UN Security Council was needed.
It will also look at the equipment supplied to British troops, amid claims they were not given adequate protection, and the preparations for the occupation which saw Iraq descend into a bloody civil war in which tens of thousands - some estimates say hundreds of thousands - of civilians died.