Congress declares war, provides an army, maintains a navy, provides for the common defense and prescribes Articles of War. But Congress is NOT the Commander-in-Chief. Only the President has the power of Commander in Chief, which includes absolute control over military strategy and the prosecution of war. It has always been intended as such as stated in Federalist 74:
"THE President of the United States is to be ``commander-in-chief of the army and navy of the United States, and of the militia of the several States when called into the actual service of the United States.'' The propriety of this provision is so evident in itself, and it is, at the same time, so consonant to the precedents of the State constitutions in general, that little need be said to explain or enforce it. Even those of them which have, in other respects, coupled the chief magistrate with a council, have for the most part concentrated the military authority in him alone. Of all the cares or concerns of government, the direction of war most peculiarly demands those qualities which distinguish the exercise of power by a single hand. The direction of war implies the direction of the common strength; and the power of directing and employing the common strength, forms a usual and essential part in the definition of the executive authority."
While Congress has the power to commence hostilities and to fund them, there is not and never has been Constitutional authority for Congress to "direct the president" in regard to conduct of military operations.