Is there anything more self-serving than Don Rumsfeld saying his worst day as defense secretary was when he learned of the Abu Ghraib abuses? (And which day was that exactly?) Worse than the attacks on 9/11, which killed nearly 3,000 people, a day on which a jetliner crashed into the Pentagon while Rumsfeld was in his office there?
No secretary of defense would subordinate the worst attack on the U.S. homeland in modern times to what Rumsfeld himself has called isolated incidents of abuse by low-level soldiers. That is, unless that secretary of defense was legally or morally culpable for that abuse, or as I'm sure is the case here, he is convinced that Abu Ghraib will be the symbol of his legacy and of the great failure that the Iraq adventure has become.
In either case, it says all you need to know about Rumsfeld that he doesn't consider 9/11 his worst day as secretary of defense.