On March 21, President Bush officially informed Congress that he had “directed U.S. Armed Forces, operating with other coalition forces, to commence combat operations on March 19, 2003, against Iraq.”

By informing Congress, the president complied with the relevant requirements of the War Powers Resolution of 1973 and two Congressional resolutions authorizing the use of military force against Iraq. Although some domestic and international critics might wish to characterize the conflict in Iraq as “Mr. Bush’s War,” much as opponents ridiculed the War of 1812 as “Mr. Madison’s War” for President James Madison, the fact remains that Congress and the chief executive each have fulfilled its constitutional responsibilities in the exercise of the war-making power.

The relative responsibilities of Congress and the president when it comes to war have been a source of debate and disagreement throughout American history. The Constitution divides the war power between Congress and the president: Congress has the right “to declare war” as opposed to the right to “make” or wage war, which resides with the president as commander in chief.

But therein lay the seed of discord. Former Presidents Thomas Jefferson and Madison, for example, argued that reserving to Congress the right to declare war put a powerful brake upon executive abuse of the war power. “The Executive is the branch of power most interested in war and most prone to it,” Madison observed. “[The Constitution] has accordingly, with studied care, vested the question of war in the Legislature.” Alexander Hamilton, on the other hand, contended that the distinction between offensive and defensive war mitigated the restrictions on the executive: “When a foreign nation declares or openly and avowedly makes war upon the United States, they are then by the very fact already at war and any declaration on the part of Congress is nugatory; it is at least unnecessary.”

Hamilton’s view seems to have been borne out by history. Congress has declared war in only five of the various wars, insurrections and armed interventions in American history — the War of 1812, the Mexican War, the Spanish-American War, World War I and World War II. Far more military actions elicited no Congressional declaration of war, including the Barbary wars, the Civil War, the many military campaigns against American Indians, the Philippine insurrection, the various Mexican-American clashes of 1914-17 and other armed interventions in Latin American countries, the Korean War, and the military actions in Vietnam, Grenada, Panama, Somalia, Kosovo, the Persian Gulf and Afghanistan.

Beginning with the conflict in Vietnam, specific Congressional resolutions have authorized the president to use military force overseas. The 1964 Gulf of Tonkin Resolution authorized the use of force “as the President determines” to defend South Vietnam. Undersecretary of State Nicholas Katzenbach later argued that the resolution was the “functional equivalent” of a declaration of war, to which Senate Foreign Relations Chairman J.W. Fulbright (D-Ark.) responded that “the question of authority to commit the United States to war is in need of clarification.” The War Powers Resolution of 1973 attempted that clarification, although it also remains a subject of debate.

The resolution provides the current framework for the use of military force overseas. It specifically recognizes only three conditions under which the president can commit the military to combat: a Congressional declaration of war, a specific statutory authorization, or a national emergency created by an attack on the United States, its territories, or armed forces. The War Powers Resolution mandates that the president “consult regularly” with Congress to ensure that the “collective judgment” of both will be brought to bear on the use of military force.

The absence of a Congressional declaration of war, however, does not mean that Congress has abdicated its constitutional responsibility. The power of the purse and oversight of the military gives Congress the means to influence, even curtail, when and how force is used. Although historically Congress has acquiesced in the presidential power to wage war, it has reserved the right to question and oppose how that power is exercised.

At times, Members of Congress have voiced strong opposition to presidential war policies. During the War of 1812, for example, Congress rejected several of Madison’s appointments and refused to pass a conscription bill to fill the depleted ranks of the Army. Northern Whigs opposed the Mexican War, with a young then-Rep. Abraham Lincoln offering his “Spot Resolutions” challenging President James Polk to affix the spot on American soil where Mexican troops had precipitated the war. The House attached the Wilmot Proviso to two appropriations bills to prohibit slavery in any territory acquired from Mexico (though neither bill passed the Senate), and in January 1848 the House passed a resolution stating that the war had been “unnecessarily and unconstitutionally begun by the President of the United States.” During the Civil War, the Joint Committee on the Conduct of the War held highly publicized investigations of the loyalties of government employees, war contracts and battle plans in an effort to influence President Lincoln’s prosecution of the war.

More often in American history, Congress has voiced its support, or at the very least its acquiescence, by appropriating funds for combat operations. In the 1790s, for example, Congress ordered the construction of several Naval frigates, including the USS Constitution, to combat the French threat to American maritime commerce.

Congress also has used its oversight and investigative powers to support the military during wartime. The Senate Special Committee to Investigate the National Defense Program during World War II was perhaps the most notable example. Better known as the Truman Committee, after its first chairman, the committee worked closely with the Roosevelt administration to implement war mobilization and eliminate wasteful practices.

Perhaps most dramatically, Congressional support has been demonstrated by Members who leave Congress to enlist in the military. Rep. Edward Baker (Whig-Ill.), for example, resigned from the House in 1846 to lead a regiment of volunteers in the Mexican War. He was later elected to fill a Senate vacancy in 1859 but once again left his seat to command a Pennsylvania regiment in the Civil War; he died leading an attack at the Battle of Ball’s Bluff in 1861. Several Members served during World War II, with then Rep.-Lyndon B. Johnson being the first to enlist in the armed forces after the war began.

If “war is politics by other means,” as Clausewitz observed, then in a democracy the invocation and exercise of the war power is rightly the province of both the legislative and executive branches. The degree to which the executive’s conduct of foreign affairs leads the nation down the “slippery slope” to war remains a legitimate subject for debate. But the role of Congress in time of war ensures that the collective judgment not only of the government but also of the people will be brought to bear on how war is declared and waged. Those who attribute war to presidential action alone fundamentally misread the nature of the U.S. government.

Donald R. Kennon is the historian for the U.S. Capitol Historical Society.