"and even in war did not seek massive annihilation of the enemy (although, in the brutal arithmetic of war, that ensures a better chance of successful occupation later on). "

So I've heard it said, but I doubt it's true. With a historical view, I think the occupation of Iraq will be one the shortest of it's kind. And "massive annihilation" will be seen something that would extend occupation. And I don't think we really want a "successful occupation" as much as enough stability so that Iraqis can form a govt.
I think history will show that we fought two armies in Iraq- the conventional army and a similar type of army that Bin Ladin wanted to defend Saudi Arabia from Saddam's aggression. A similar mistake that Generals commonly make, Bin Ladin wanted to fight a war like it was fought in Afghanistan. Of course, if Bin Ladin had his way, he wouldn't have defended Saudi Arabia, but rather completely destroyed the country.
So if we had gone the massive annihilation route, then we would have merely made Iraq more closely resemble Afghanistan- and we would still be fighting the terrorists and dead enders.