In the same message I informed Congress that the amount of the "loan" which would be required for the further prosecution of the war might be "reduced by whatever amount of expenditures can be saved by military contributions collected in Mexico," and that "the most rigorous measures for the augmentation of these contributions have been directed, and a very considerable sum is expected from that source." The Secretary of the Treasury, in his annual report of that year, in making his estimate of the amount of loan which would probably be required, reduced the sum in consideration of the amount which would probably be derived from these contributions, and Congress authorized the loan upon this reduced estimate.
In the message of the 10th of February, 1848, to the Senate, it was stated that—
No principle is better established than that a nation at war has the right of shifting the burden off itself and imposing it on the enemy by exacting military contributions. The mode of making such exactions must be left to the discretion of the conqueror, but it should be exercised in a manner conformable to the rules of civilized warfare.
The right to levy these contributions is essential to the successful prosecution of war in an enemy's country, and the practice of nations has been in accordance with this principle. It is as clearly necessary as the right to fight battles, and its exercise is often essential to the subsistence of the army.
Entertaining no doubt that the military right to exclude commerce altogether from the ports of the enemy in our military occupation included the minor right of admitting it under prescribed conditions, it became an important question at the date of the order whether there should be a discrimination between vessels and cargoes belonging to citizens of the United States and vessels and cargoes belonging to neutral nations.
In the message to the House of Representatives of the 24th of July, 1848, it was stated that—
It is from the same source of authority that we derive the unquestioned right, after the war has been declared by Congress, to blockade the ports and coasts of the enemy, to capture his towns, cities, and provinces, and to levy contributions upon him for the support of our Army. Of the same character with these is the right to subject to our temporary military government the conquered territories of our enemy. They are all belligerent rights, and their exercise is as essential to the successful prosecution of a foreign war as the right to fight battles.
By the Constitution the power to "declare war" is vested in Congress, and by the same instrument it is provided that "the President shall be Commander in Chief of the Army and Navy of the United States" and that "he shall take care that the laws be faithfully executed."
When Congress have exerted their power by declaring war against a foreign nation, it is the duty of the President to prosecute it. The Constitution has prescribed no particular mode in which he shall perform this duty. The manner of conducting the war is not defined by the Constitution. The term war used in that instrument has a well-understood meaning among nations. That meaning is derived from the laws of nations, a code which is recognized by all civilized powers as being obligatory in a state of war. The power is derived from the Constitution and the manner of exercising it is regulated by the laws of nations. When Congress have declared war, they in effect make it the duty of the President in prosecuting it, by land and sea, to resort to all the modes and to exercise all the powers and rights which other nations at war possess. He is invested with the same power in this respect as if he were personally present commanding our fleets by sea or our armies by land. He may conduct the war by issuing orders for fighting battles, besieging and capturing cities, conquering and holding the provinces of the enemy, or by capturing his vessels and other property on the high seas. But these are not the only modes of prosecuting war which are recognized by the laws of nations and to which he is authorized to resort. The levy of contributions on the enemy is a right of war well established and universally acknowledged among nations, and one which every belligerent possessing the ability may properly exercise. The most approved writers on public law admit and vindicate this right as consonant with reason, justice, and humanity.
No principle is better established than that—