You're running a war. It isn't going well. Your troops are trapped in swirling dust populated by hostile Pashtuns around Kandahar. When the local Taliban need to, they can slip easily across the border into the safety of Pakistan.
Worst, you've agreed to a deadline, you've stated in public that you'll be finished with counter-insurgency by summer 2011.
What do you do?
You either need to be fired, in which case it will be President Obama's fault for nicking the indispensable man (heh) on the threshold of success. Or you need to paint the President and other civilian authorities into a corner so that they'll have to acquiesce to grinding more meat in Afghanistan. You care about your place in history and even project it on your government:
“[Ambassador Karl Eikenberry]’s one that covers his flanks for the history books,” General McChrystal is quoted as saying. “Now, if we fail, they can say, ‘I told you so.’ ”You think Obama can't afford to be a firm manager of the military in the run-up to the difficult 2010 midterms. So you thumb your nose and dare him to fire you.
It's time to reassert civilian control of the military.
Update (6/25): Chan Lowe sees McChrystal's escape too.