I see in your apologetics, you also failed to cite the constitutional authority.
Actually it does not.
About this you are right. My phrasing was inaccurate.
Authority to do what? To order the army and navy to blockade the southern coast? He has that authority as commander-in-chief of the armed forces, as per Article II, Section 2. The responsibility to combat rebellion? He had that authority as per the Militia Act of 1795. What authority are you referring to?