Whenever during any insurrection against the Government of the United States, after the President shall have declared by proclamation that the laws of the United States are opposed, and the execution thereof obstructed, by combinations too powerful to be suppressed by the ordinary course of judicial proceedings, or by the power vested in the marshals by law, any person, or his agent, attorney, or employee, purchases or acquires, sells or gives, any property of whatsoever kind or description, with intent to use or employ the same, or suffers the same to be used or employed in aiding, abetting, or promoting such insurrection or resistance to the laws, or any person engaged therein; or being the owner of any such property, knowingly uses or employs, or consents to such use or employment of the same, all such property shall be lawful subject of prize and capture wherever found; and it shall be the duty of the President to cause the same to be seized, confiscated, and condemned.