Plugging his new book The Gamble on the Iraq surge, the Washington Post's Thomas Ricks offers a jaw-dropping account of the critical decision to pay off Sunni insurgents. Contrary to George W. Bush's "decider" myth, it was David Petraeus who simply informed the President of that defining change in tactics the General implemented on his own in 2006. As it turns out, from Paul Bremer's catastrophic disbanding of the Iraqi army in 2003 to key elements of the surge itself, Bush was the UNODIR President, blissfully unaware of subordinates moving ahead "unless otherwise directed."
As Ricks recounted for Jon Stewart on the Daily Show, General Petraeus told Bush only after the fact about his move to bribe the insurgents, the Sunni Awakening that preceded the January 2007 American troop escalation by months (video here):

STEWART: It was fascinating to me that Petraeus goes above the chain of command, goes above his commanding officer, directly to the President and even does things the President doesn't know he's doing, like paying the insurgents, the people who are trying to kill us.
RICKS: That was another odd moment of the interview [with Petraeus]...Last October, I said, "how did you break it to the President that you were going to put the Sunni insurgency on the payroll. How did you sell him on, 'I'm going to put the evil doers on salary?'" He said, "Oh, I didn't." This was the biggest policy decision of the last two years and you didn't ask? He said, "no, it was within my existing authority." OK!
STEWART: But did he tell the President at some point?
RICKS: I think they mentioned it later on...

In his book (Angler) on the Cheney vice presidency Ricks' WaPo colleague Barton Gellman related the central role the military's notion of UNODIR for the real players in the Bush administration:

With a mischievous smile, Petraeus described UNODIR as a valuable if risky tool for the commander who values autonomy. The way it works is, you take initiative in the heat of the moment. Then you send a well-timed message ("Unless otherwise directed, I will continue to..."). Hearing no objection, you have a patina of authority for decisions that higher headquarters have neither approved nor forbidden. In less skillful hands, this can easily end a career, but Petraeus went on to four stars and a job as chief of U.S. Central Command.
Cheney did well by it, too. He was the UNODIR vice president writ large. He did not defy the commander in chief, but he certainly did not sit around waiting for orders. If the president did not like the results, what was the worst that could happen? As Cheney understood very well, a vice president can't be fired.

As it turns out, Dick Cheney wasn't the first and David Petraeus wasn't the last figure to proceed with make-or-break decisions before getting President Bush's ex post facto assent. Among them was L. Paul Bremer, viceroy of the Coalition Provisional Authority (CPA) whose disastrous May 2003 decision to dissolve the Iraqi army nearly broke the American project in Iraq.
Using letters provided by Bremer, the New York Times later documented that President Bush indeed casually approved Bremer's May 2003 plan to disband the Iraqi military. Bremer released both his May 22, 2003 letter detailing his plans and progress on de-Baathification and the dissolution of Saddam's army, as well as President Bush's May 23rd response.
In his May 22 letter, Bremer informs Bush that:

"We must make it clear to everyone that we mean business: that Saddam and the Baathists are finished...I will parallel this step [de-Baathification] with an even more robust measure dissolving Saddam's military and intelligence structures to emphasize that we mean business."

In his shockingly brief May 23 response, Bush seemingly blesses Bremer's fateful step to dissolve the Iraqi military:

"Your leadership is apparent. You have quickly made a positive and significant impact. You have my full support and confidence. You also have the backing of our Administration that knows our work will take time."

As a nonchalant Bush told biographer Robert Draper in 2007, "The policy was to keep the army intact; didn't happen" and "Yeah, I can't remember, I'm sure I said, 'This is the policy, what happened?'"
And so it went. As the United States approach crucial forks in the road in Iraq, President Bush was asleep at the switch, waking only when initiative-taking subordinates tipped him off to their progress during his slumbers. For good or ill, usually ill, they moved forward - unless otherwise directed.