The military should follow all legal orders of the President. Period. Except for some demented leftists, I don't think anybody's arguing that Obama's military strategy in Afghanistan is illegal -- just dangerous and counterproductive.
If an Officer believes an order is ruinous, then he should resign his Commission and state so publicly. But insubordination or mutiny means the end of the Republic.
BTW, I think McA should have gone ahead and bombed the crap out of North Korea and the Chinese troops screaming down towards the south as he proposed. Truman was wrong, as history has well proven.
So in other words, you think the Army should run the country. Not only does that violate the Constitution, but it's a really bad long term decision. Abraham Lincoln made plenty of terrible military decisions, but I think we're far better off today than if the Army of the Potomac had gone rogue and taken over.
An officer swears an oath to the constitution not the President. Americans don't recognize omnipotent leaders, we recognize the rule of law.