Commander in Chief, President as. The Constitution (Article II, section 2) specifies that The President shall 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. A commander-in-chief, also called supreme commander, is the person that exercises supreme command and control over an armed forces or a military branch. Article II Section 2 of the U.S. Constitution, the Commander in Chief clause, states that "[t]he President shall 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 President shall be Commander in Chief of the Army and Navy of the United States Article II, Section 1, Clause 1, vests the entirety of the "executive Power" in a single person, the President of the United States. Presidential power advocates argue that this provision