Article I, Section 8, Clause 11:
[The Congress shall have Power . . .] To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water; . . .
Three different views regarding the source of the war power found expression in the early years of the Constitution and continued to vie for supremacy for nearly a century and a half. Writing in The Federalist, 1 Hamilton elaborated the theory that the war power is an aggregate of the particular powers granted by Article I, § 8. Not many years later, in 1795, the argument was advanced that the war power of the National Government is an attribute of sovereignty and hence not dependent upon the affirmative grants of the written Constitution. 2 Chief Justice Marshall appears to have taken a still different view, namely that the power to wage war is implied from the power to declare it. In McCulloch v. Maryland, 3 he listed the power
to declare and conduct a war 4 as one of the
enumerated powers from which the authority to charter the Bank of the United States was deduced. During the era of the Civil War, the two latter theories were both given countenance by the Supreme Court. Speaking for four Justices in Ex parte Milligan, Chief Justice Chase described the power to declare war as
to all legislation essential to the prosecution of war with vigor and success, except such as interferes with the command of the forces and conduct of campaigns. 5 In another case, adopting the terminology used by Lincoln in his Message to Congress on July 4, 1861, 6 the Court referred to
the war power as a single unified power. 7