The constitutional commander-in-chief of the army and navy of the United States, and of the militia of the several States, when called into the service of the United States, is the President17 Through, or under, his orders, therefore, all military operations in times of peace, as well as of war, are conducted He has within his control the disposition of troops, the direction of vessels of war and the planning and execution of campaigns. With Congress, however, lies the authority to lay down the rules governing the organization and maintenance of the military forces, the determination of their number, the fixing of the man-mer in which they shall be armed and equipped, the establishment of forts, hospitals, arsenals, etc., and, of course, the voting of appropriations for all military purposes.18

17 Art. II, Sec. II, CI. 1.

18 The distinction of congressional from presidential powers in military matters is drawn by the Supreme Court in Ex parte Milligan, 4 Wall. 2; 18 L. ed. 281, in the following words:

"Congress has the power not only to raise and support and govern armies, but to declare war. It has, therefore, the power to provide by law for carrying on war. This power necessarily extends to all legislation essential to the prosecution of war with vigor and success, except such as interferes with the command of force9 and the conduct of campaigns. That power and duty belong to the President as commander-in-chief. Both these powers are derived from the Constitution, but neither is defined by that instrument. Their extent must be determined by their nature, and by the principles of our institutions.

The power to make the necessary laws is in Congress, the power to execute in the President. Both powers imply many subordinate and auxiliary powers. Each includes all authority essential to its due exercise. But neither can the President, in war more than in peace, intrude upon the proper authority of Congress, nor Congress upon the proper authority of the President. Both are servants of the people, whose will is expressed in the fundamental law. Congress cannot direct the conduct of campaigns, nor can the President, or any commander under him, without the sanction of Congress, institute tribunals for the trial and punishment of officials, either soldiers or civilians, unless in cases of a controlling necessity, which justifies what it compels, or at least insures acts of indemnity from the justice of the legislature."

With respect to many matters of detail Congress has delegated to the President and to his executive subordinates the establishment of administrative orders for the government of the land and naval forces which it might constitutionally itself provide, but which in fact it is either impossible or unwise for it to attempt to do. All orders of the President, or of the Secretary of War issued under his authority whether given by virtue of his constitutional office as commander-in-chief or of his statutory powers have the full force of law.19 But in all cases these orders must, if issued by virtue of authority congressionally given, pursue the terms of the granting statute; and if issued by virtue of his constitutional authority, be in accordance with the generally accepted principles of international law and custom. Where this is not done, they will not justify the acts of subordinates acting under them.20