The problem is fighting the "war" is the easy part. The "war" in Iraq 2 lasted the first 17 days. The next 6 years were combat operations in support of the "peace". Commanders would have be professionally negligent if they did not understand and adapt their orders to recognize and deal with the political-military nexus that is implicit in virtually every situation. Advice from the POLAD/LEGAD is vital to fully understanding the battle space.
But they were negligent in not having a plan in place to ensure a stable and continued existence. They might have won the war in 17 days, but they lost it in the following months, they stood by as rape, murder and looting went on and the civilian population came round to the realisation they no longer had safety, drinking water, working sewage systems, food, medical facilities, heating and power. Even during ww2 it was realised you had to work with the remaining infrastructure in Germany while you weeded out the bad guys, something sadly that never happened in Iraq, no wonder it became a breeding ground for terrorism, hate and mistrust and took 6 years to get out of.