The Preamble's declaration that the U.S. Constitution was established in part to "provide for the common defense" refers to the authority it grants the federal government to maintain a military for use in defense of the union. Specifically, Congress is granted authority under Article I to raise and maintain an army, while the president is named its commander-in-chief by Article II.Continue Reading
Alexander Hamilton in Federalist No. 23 described provision of the common defense as a principle purpose of the union. Once it has been decided that a federal government is to be entrusted with the common defense, he argued, “that government ought to be clothed with all the powers requisite to complete execution of its trust.” The powers he describes as essential include the authority to raise armies and build fleets, along with the means to support and maintain both.
Prior to the adoption of the Constitution, individual states were responsible for their own defense. The Articles of Confederation had previously sought to make the federal government responsible for defense, but in practice failed to do so. Lacking sufficient power and means to make and enforce federal policy, the federal government under the Articles of Confederation was unable to prevent states from engaging in their own foreign policy and diplomacy. Problems created under this system convinced leaders a stronger central government was needed, which included giving it the unambiguous power and responsibility to defend the nation.Learn more about The Constitution