Okay, let's take this to a high level abstraction.
Okay, as Milefile said, history is written by the winner, or as Orwell perhaps more eloquently stated "Whoever controls the present controls the past." That quote might be slightly innacurate, so don't flame me for that one.
This means, in short, that if you win, then you were right. End of story. Subsequent generations, at least those controlled by the same regime, will believe that, because they had it drilled into them from birth. So, in effect, as far as progeny is concerned, there is no right or wrong, simply who won, and how completely. Therefore, the only true failure or a war which you won is to not have won it completely, as we have done in Iraq, because their history will never truly depict the United States as its savior. Whether or not this is true is not the issue. Because, in all honesty, what you think is of far less importance than what subsequent generations think, because it is their thought that will shape foreign policy. The only war crime, following this logic, is losing. Had Germany won WWII, horrid stories about the Halocaust would not exist. To provide an example, the United States undeniably won the Pacific Theater of WWII. In the United States, at least, the atomic bombs that we dropped on Japan, killing thousands upon thousands of civillians, an obviously morally reprehensible act, is rarely considered so within US borders. Most people I know, and probably most that I am likely to know, have never considered the act in this light, and use the "well, we won," argument. Of course, they don't use the correct logic behind this viewpoint, and it comes more from the blind patriotism that doctored history is written to inspire than any true thought on the part of the commenter. So, although the war in Iraq is not yet over, it has been partially successful, but, of course, not completely.
To why history is written in this manner, I'll take a simple historical example. During the course of the Vietnam war, it was more likely to be supported by the higher educated, rather than less. The longer one spends around History books, the more one remembers and believes out of them. So, in the end, the winner wins, and the loser loses. No matter what.