You can tell in his press conferences: Rumsfeld always wants to score an immediate point, squelch any concern, and repeat his verse about "the outcome is not in doubt." That's the problem: the man has no doubts, because he can't see far enough ahead. Not far enough to think how his zingers ("It's hard to take France serious" was one of them) will affect longer-range strategy -- because he has no longer-range strategy.
A smarter man would not have trashed the diplomacy that was effectively isolating Saddam. And, after grossly offending France, Russia, China and even Turkey, he would have at least avoided insulting his one remaining ally of importance, Tony Blair, by saying "we" (the US government) didn't really need them. And even after all those blunders, a smarter man still could have declared victory a month ago. He could have said, "Thanks to the immense show of force by American and British troops and the UN's vigorous inspection program, we -- and the international community -- have won. There is no need now to invade Iraq; we have Saddam tightly contained and his weapons closely observed."
But no. This is a man who doesn't know when he has won, because he has never thought out what we're fighting for. And now he doesn't realize that he and all of us have lost: lost our best chance of achieving peace and democratization in the region. But very likely those were never his goals, because there is really no strategy at all. Just more zingers -- some of them carrying tons of explosives -- with no thought for what happens next.