Fred Hiatt of the Washington Post, in the simplest, most straightforward way, has it just about right:

However historians assess Bush’s policies on Iraq — stretching back to the invasion, the failure to commit enough troops, the delays in acknowledging mistakes — his insistence 20 months ago on a new strategy requiring more troops will be seen as an act of remarkable courage. With public opinion, Congress, the bipartisan Iraq Study Group and most of his administration pushing toward a “consensus” option of managed failure, Bush insisted on a policy that would yet provide a chance of success.

He gives the credit to Bush, to Stephen Hadley, and to the other lonely warriors for the surge:

Hadley wasn’t alone in his insight. Sens. John McCain and Joe Lieberman, former senator Chuck Robb, NSC staffer Meghan O’Sullivan, strategist Frederick Kagan of the American Enterprise Institute, retired Army general Jack Keane and a few others were pushing in the same direction. Eventually it would take the new leadership of Gen. David Petraeus and Ambassador Ryan Crocker in Iraq to translate opportunity into actual strategy.

The rest is (ahem) commentary . . .