It's in Article I, ma'am. Article I is the legislative Article.Yes, twodees, and Congress authorized the use of force which puts the military into play, and empowers the President as Commander in Chief.
You obviously don't understand the doctrine of separation of powers. Congress is not empowered to delegate any of their powers to another branch of government. Besides, Lincoln pulled all this nonsense while Congress was in recess. Show me where Congress finally got around to declaring war for Lincoln.
Lincoln usurped the powers of the other two branches of government and arrogated powers to himself that were never delegated to any branch of government in the Constitution. That is irrefutable.