Once Upon a Time in Iraq is the most searing anti-war documentary I have seen. In five parts on Mondays on BBC2, it is not bangs, screams and tears. The searing is not visceral. It is intellectual. In among the footage of the 2003 war, we hear simply the calm narrative of people whose lives were traumatised by the conflict, who witnessed the gut-wrenching obscenity of two great democracies using death and destruction to pursue their leaders’ political agenda. It shows that the morality of power projection has not advanced since the middle ages. A corpse is still a corpse. Now at least we get to hear from the victims. The director, James Bluemel, approached the war not through those who ordered or opposed it, but through the recollections of the ordinary civilians, soldiers and reporters who experienced it. They were not war’s actors, they were its consequences. They leave us to draw our own conclusions. Through the narrative we thus grow to know Waleed Nesyif, a teenager once in love with all things American, who cheered the invasion. He then visited what had been a family living in the desert, utterly obliterated by three invasion gunships. We see American soldiers standing by while looters tear apart downtown Baghdad. A soldier says he was told to protect only the oil ministry. We hear Um Qusay, a dignified elderly woman, who welcomed Saddam’s going but then had to face its appalling consequence, the rise and rule of Isis. Issam al Rawi was a Saddam admirer who had predicted only evil would come of his death – and was right. We cut to a marine sergeant, Rudy Reyes, telling of the elimination of a vehicle full of women and children for failing to read a roadblock sign. “It has to be worth it,” he says, swigging tequila, “or what’s the alternative?” This is what retired general Sir Rupert Smith has called “war among the peoples” – an open-ended, primarily political conflict, conducted in cities, rather than on battlefields. Every military library groans with warnings of its danger. I visited Baghdad shortly after the invasion to interview its governor, Paul Bremer, and was left gasping at the lawlessness. Outside the fortified green zone, there were no police. We saw shops looted, Baghdad’s museum gutted. Tanks crashed down city streets. Disillusion was instantaneous. A young man, Ahmad al-Basheer, recalls: “I was full of hope that this was going to be a new country.” But as the ferocity of the destruction mounted, he sensed, “it’s just never gonna happen, it’s never gonna be safe again”. The invaders were not just toppling a dictator. Public buildings were destroyed with “shock and awe” bombing. Families were terrorised with nocturnal searches, with soldiers smashing into women’s bedrooms. Every Ba’athist had to be sacked, from the police to the university, which meant the command structure of civil society collapsed. All Iraqis were punished for the sins of Saddam. Again, it was medieval. When I asked Bremer how he could possibly restore law and order that way, I shall not forget his shrug. He was obeying orders from a Washington in thrall to rightwing ideologues. They ignored what every student of war knows: that for the victims, safety always takes precedence over freedom, life over liberty. Invading Iraq was not the worst thing America did. Far worse was the anarchy. In a matter of months, anarchy had become the recruiting sergeant of rebellion. The 2003 war was truly a replica Fourth Crusade, a wild military adventure that went terribly wrong. As copious histories have pointed out, after Afghanistan in 2001 George W Bush was spoiling for another fight. Finding weapons of mass destruction and “bringing freedom” were excuses. The giveaway was Bush’s declaration of “mission accomplished” within weeks of the invasion. That was his mission. The consequence lay ahead. At one point in the documentary, the CIA man who interrogated Saddam, John Nixon, recalls the prisoner’s boast that he had kept Shia and Sunni at peace. The peace, was of course, a brutalised one, maintained through fear and atrocity. But he also said: “Now you have come, Iraq will become a playground for forces that are looking to build hatred and unleash terrorism.” And this is indeed what came to pass. When Barack Obama finally withdrew US forces in 2011, the corrupt and insecure regime collapsed. There then arose the most sickening insurgency of modern times, Isis. Playing blame games with history is in vogue. It substitutes insight with hindsight, applying the distorting lens of today’s values to past events. But when does current responsibility lapse and history begin? Bluemel interviews only people who could not sensibly be held “to blame”. Many were clearly aware they were party to some terrible mistake. But blame was above their pay grade. War gives a licence to blind obedience. Patriotism and loyalty devolve responsibility upwards. The boss takes the blame. Britain had no reason to take part in this fiasco. Widespread comment at the time was deeply sceptical. While British neutrality would not have stopped Bush in his tracks, it would have deprived it of the legitimacy of a “coalition”. The conventional wisdom is to blame Tony Blair. This will not do. Blair was certainly the prime mover, but he did not assert prerogative discretion. His cabinet overwhelmingly agreed with him, with just three ministerial resignations. Then in March 2003, parliament met and 412 MPs, Labour and Tory, approved the invasion. They knew the grounds were spurious, that Saddam did not “imminently” threaten Britain. They were swept up by the emotion of war. Democracy’s supposed check on the executive proved worthless. The only comfort was that MPs learned one lesson. When David Cameron asked permission for a deranged war with Syria in 2013, the Commons mercifully said no. This documentary (and the associated book) brings home the full enormity of the Iraq war. A phoney freedom cost an estimated quarter of a million Iraqis their lives. It destabilised a region and undoubtedly contributed to the collapse of order in Syria. It did nothing to halt terrorism in Britain or elsewhere, if anything the reverse. As for the financial cost, the fiasco consumed some $3tn. What those trillions might have done for good in the world is unimaginable. In sum, the Iraq war deserves to rank with the greatest – and most senseless – war crimes of our age. I am not of a punitive nature, but I find it extraordinary that the errors and horrors illustrated in this documentary should go unpunished. As for those who were “only obeying orders”, 1930s Europe was surely warning enough. War is too awful – and too seductive to a populist leader – for its risks and causes to escape searching democratic scrutiny. It rarely gets it. More than 15 years on, this film will have to do.