Secretary of War or Secretary of Defense: the cabinet position is one where one serves at the pleasure of the President. If the President isn't pleased, you get sacked.
True enough. But then again that's true of every cabinet level position. The interesting part is that no one seems to want to take over the SecDef job. Obama seems to have so poisoned those waters with his micromanagement, that everyone so far has turned down the job. It'll be interesting to see who finally decides to be Obama's yes man at SecDef.