In response to the lynching of four American security contractors, US forces were ordered to "clean out" Fallujah, over the protests of the Marine commander on the ground, who argued that months of painstaking efforts to win hearts and minds would be destroyed.
"The decision was political, not military," said Toby Dodge of Queen Mary College, London University, who went to Downing Street with other Iraq experts before the war to warn Mr Blair of the perils of an invasion. "It was taken in the Oval Office."
But after three weeks of heavy fighting, and correspondingly high casualties, the White House lost its nerve. The Marines, who lost 600 men, believed they were on the point of seizing the town when they were ordered to hand over to an "Iraqi brigade" commanded by a general from the Saddam era, which promptly yielded control back to the insurgents.
In the midst of this disaster, the Prime Minister was at the White House. That Britain was concerned about the conduct of the fighting was revealed in a leaked Foreign Office memo the following month. This said: "Heavy-handed US military tactics in Fallujah and Najaf, some weeks ago, have fuelled both Sunni and Shia opposition to the coalition, and lost us much public support inside Iraq."
...update: the 600 number is bogus, didn't notice it on the first read. Don't know if this was just a typo or what. In any case it wasn't the reason why I linked to the story but it certainly raises questions about the legitimacy of the reporting.