A friend e-mails:

I agree with Foster’s emailer. McChrystal has to go or Obama looks fatally weak.
There are two applicable movie scenes. Don’t look for exact parallels (no character corresponds to McChrystal or Obama exactly). But they both clearly express the importance of the military being subordinate to civilian control . . . even if the civilians are wrong or weak.
13 Days – McNamara stands up to an Admiral.
Seven Days in May – (Spoilers within – but the movie is almost 50 years old.) A very unpopular president negotiates a very unpopular treaty seen as capitulation to the Soviets. Burt Lancaster’s popular general character literally plots a secret/surprise military coup and is about to put it into action. But the President has discovered it.