The great mistake of this war was making it about WMD in the first place. If we had simply said we were going into finish HW's job and remove Saddam, then we wouldn't be in the same political mess we're in now. But instead we (a) made the issue about WMDs, which turned out to be a trillion-dollar snipe hunt, and (b) we engaged in a full de-Baathification of the country afterward, ruining the infrastructure necessary to provide stability in the country. This latter process is the most grievous because Dubya didn't understand that there was a difference between a Sunni and a Shiite at the time we were preparing to invade. I'm not making that up. He had no concept whatsoever that there are denominal differences in Islam just like there are in Christianity and Judaism. Some RADICAL differences. Google link about Bush's ignorance on the matter. Read 'em yourself.

Few people on this planet will stand up for Saddam. But there is every reason in the world to criticize the decision to invade when we were engaged in more important matters elsewhere, the execution of the post-war "plan" and the stubborn adherence to a failed policy because to admit a mistake opens one up to liabilities of the gravest sort. Mission Accomplished indeed.