As pressure for yet another strategic change in Iraq grows in Washington and Congress's desire to withdraw troops grows more urgent, President Bush has been repeatedly falling back on one oft-repeated line of spin.

This time it isn't his never-ending line about needing to "defeat them abroad before they attack us at home" or his insistence that America will "stay the course" in the Middle East. Nowadays, Bush is warning his critics - indeed, everyone in the House and the Senate - that they should stop trying to "micromanage" the war. The president took another crack at lawmakers last Thursday, when he said: "I'll listen to Congress. But the idea of telling our military how to conduct operations, for example, or how to deal with troop strength, I don't think it makes sense . . . nor do I think it's a good precedent for the future."

Politicians, he keeps saying, do not have the experience and know-how of military leaders such as general David Petraeus, and it should be those "generals on the ground" who guide the strategy in Iraq, not the stuffed suits in Washington.

Coming from an administration whose most grievous errors in Iraq have come from ignoring military advice time and again, this is pretty rich. The Bush years have been dominated by a 'we know best' mentality and will be remembered for the hubris displayed by the president and his key advisors.

The assumption behind Bush's remarks - that all the military leaders in Iraq support the surge strategy - is dubious in itself. Senator John Kerry was reported in the San Francisco Chronicle on Friday saying, "No general, no administration official has come to us... in our secret briefings and said this is a winning strategy."

But the words that most damn this sudden faith in the "generals on the ground" as convenient at best and fraudulent at worst, come from the generals themselves.

Thomas E Ricks, the Washington Post's Pulitzer prize-winning Pentagon correspondent, has detailed numerous examples of military leaders being ignored by the White House in his excellent book, Fiasco.

The list of generals that the White House ignored runs all the way back to 2002, when the administration was still building its disingenuous case for war. The Joint Staff in Washington told planning officers on the staffs of senior US military commanders around the world (ie "on the ground") that the Iraq war was to be considered part of the war on terror. One of the responses from these officers questioned the order: "There is no link between Saddam Hussein and 9/11. Don't mix the two. This is going to work hell with the allies. What is going on?"

Of course, those concerns weren't heeded in Washington.

"Watching the moves towards war [in early 2003], the Army community fretted, no one more than Norman Schwarzkopf," Ricks writes. Schwarzkopf, the man who had led the first gulf war, found it "scary" that Donald Rumsfeld, Paul Wolfowitz and Douglas Feith had "ignored" the advice of senior generals.

Most notably, the administration didn't accept advice from then-US Army chief of staff general Eric Shineski that the number of troops required to occupy Iraq would need to be bigger than the number required for a successful invasion. Shineski went to Capitol Hill and said he'd need "Something on the order of several hundred thousand soldiers". Any number of generals, current and retired, said the same thing.

However two days later Wolfowitz described such predictions as "outlandish" and "wildly off the mark". He was confident that by August 2003 about 30,000 troops would suffice.

Come the invasion, the entire ground force numbered around 145,000, with 125,000US troops. It was around half of what numerous military leaders recommended. One officer from the Joint Staff told Ricks that, on troop numbers, "[the Bush administration] did not take the best military advice... I have angst every day about that. We didn't get it right and 1500 troopers [the number of US dead when at the time he was speaking] have paid a price for that."

Yet the president has the gall to say now that "the idea of telling our military... how to deal with troop strength, I don't think it makes sense". It would be nice to think that he's learnt his lesson from the invasion. Except that the same kind of mistakes were made when Fallujah exploded into insurgency in 2004. Ricks reports that "top military commanders in Iraq, including Lt. Gen. Sanchez, advised against" a swift, tough response. Marine commander major general James Mattis protested: "This is what the enemy wants." But the commander-in-chief ignored his commanders on the ground and ordered in his clobbering machine. The brutal response created more insurgents and more resentment.

Of course, generals can get it wrong. Sometimes the will of the people should take precedent over the will of the military; this is, after all, one of the reasons most democracies give civilian leaders the final say in military matters. The military has the expertise, but politicians have the mandate and are elected to exercise judgment. Bush's judgment was woeful in 2003 and again in 2004. Yet sometimes it remains a politician's duty to over-ride the military commanders for the sake of the nation, and the world. Which is exactly what congress is doing.

This post first appeared in the Guardian's Comment is Free section on July 16, 2007.