To date, twenty-nine presidents served in the military and a dozen were even general officers. Here's What You Need to Know: Not all Presidents were veterans, but being a veteran certainly gave them a leg up in the polls. President Joe Biden is the “Commander in Chief” and that is far from an honorary title. In fact, the Constitution states, “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.” Since the National Security Act of 1947, that has also been understood to mean all United States Armed Forces. Yet, the exact degree of the authority that the Constitution actually grants POTUS has been the subject of debate, especially in recent years.