And so the fallout begins. As Iraq moves into repair, the British government will have to start mending bridges with its allies. One friendship that will need close attention is with the British aid sector.
Charity law is supposed to prevent charities from taking political positions. During the attack on Iraq, charities had to tread the fine line between expressing serious concern about the human consequences of the conflict, and saying what they all really thought: that without UN backing, the war was illegal and immoral and would have disastrous consequences for their work in the Middle East and around the world.
"There are many of us who feel the war is not just illegal, it's horrific," said one insider at a leading British aid group during the conflict. "Of course corporately that's not our position."
On the surface the aid groups and Clare Short's Department for International Development make a pretty tight alliance - what one aid agency spokesperson described as a "little caucus of support". In her monthly meetings with the British Overseas Aid Group (BOAG), made up of the directors of Cafod, Save the Children, ActionAid, Christian Aid and Oxfam, Short has privately urged them to lobby the Chancellor, Gordon Brown, to release more cash for her department. In turn, BOAG members offered support during her "night of anguish" as bombing loomed without UN backing. It was Julian Filochowski, director of Cafod, who made that reassuring personal call informally urging her to stay.
But below the surface, relations are not so rosy. The aid agencies are furious that, in the run-up to the conflict, Short's department refused to release any funds to help them prepare for a humanitarian crisis. After the bombing began, when a tiny amount was made available, many refused to apply, not wanting to be tainted by funds from a government waging war.
They are also dismayed that Britain launched another war when the humanitarian fallout from the last one, in Afghanistan, had not yet been cleaned up. During the past year, due to the security vacuum outside Afghanistan's main cities, aid agency workers there, caught between warring factions that the coalition forces had promised to deal with, have faced robbery, rape and even murder.
It is for Tony Blair, however, that the aid agencies reserve their real anger. His public claim to have been running a humanitarian campaign in Iraq, while doing little of the sort, could have devastating consequences all over the world for their work. It has been well rehearsed that having the military hand out aid endangers civilians and aid workers alike. In most developing countries where British aid agencies work, the war was regarded as an imperialist invasion. Those receiving assistance from aid groups are beginning to confuse British aid with British bombs. Across the Middle East, British aid workers are finding it harder to do their work. Staff in India and Bangladesh have received hate mail.
"There's no doubt that people don't make the distinction between the British government and British aid workers," said Salil Shetty, the chief executive of ActionAid and chair of BOAG. "And of course, they don't know the difference between No 10 and the Department for International Development."
Blair's inability to confirm a UN-led reconstruction of Iraq, and a UN-led humanitarian programme, could now be the last straw in relations with the British aid sector, which until this conflict had generally offered private support to the government, and Short's department in particular.
"We are stomping our collective feet rather loudly, and it's about to come to a head," said Dominic Nutt at Christian Aid.
British aid groups just cannot stomach working in Iraq under the instruction of a US general or stooge. But nor do they want to leave the homeless and thirsty of Iraq without help.
Blair and the Foreign Secretary, Jack Straw, claimed to have done their best to push a UN-led solution to the humanitarian fallout in post-conflict Iraq. For one aid agency chief that just isn't good enough: "They said they were trying their best over a second UN resolution, and look where we are now."
Relations between the government and the British aid sector are just one addition to the war's collateral damage. Next time around, will the agencies tread so carefully between politics and charity, or will they publicly add their considerable weight to the anti-war campaign?