One more here who remembers the Baghdad going to Stalingrad idea. Certainly that seemed the best way to bleed US forces… but apparently some Iraqi units went for some conventional warfare in places and naturally got their asses handed to them. Baghdad fell as much due to lack of higher leadership than will to fight… the leaders ran and naturally the soldiers melted away.
I think many predicted a hard time keeping the peace… that the Sunnis would be the major participants wasn’t foreseen though… since they would have been mostly killed in the battles for Baghdad ? Shia religious agitation would have seemed a more likely cause.