(March 2005) As military reservists continue to constitute nearly 40 percent of the 150,000 U.S. forces now deployed in Iraq, public debate continues to grow about the military’s current reliance on the reserves. Some analysts have even called the military’s consideration of extended call-ups for reservists part of a “back-door” draft. But the widely held expectation that reserve forces will be used sparingly in wartime is contradicted by the history of the reserves and of U.S. military planning.

Except for Vietnam, Reserves Often a Major Mobilization Source

From the birth of the American Republic until World War II, in the absence of a large standing army, the militia, which evolved into the National Guard, was the major mobilization source for trained military personnel. State militias supplied 96 percent of the Union army and 80 percent of Confederate troops in the Civil War. Around 400,000 Guardsmen served in World War I, representing the largest state contribution to overseas operations during the 20th century. And almost 300,000 Guardsmen served in World War II.

With the establishment of a standing U.S. force for the Cold War after World War II, the reserves came to be looked on as an expansion base for another European war.1 However, in 1950, the United States was faced with a new contingency: a “limited war” on the Korean peninsula. Reservists accounted for more than one-third of the first-year mobilization for that war, which lasted until 1953.

But the Vietnam War changed military policy toward use of the reserves. First, the manpower supply available in the baby-boom generation for conscription was deemed ample for the war effort. Second, Presidents Kennedy and Johnson wanted to communicate to the American people their intent to limit U.S. involvement in Vietnam. Thus, the reserves were not mobilized during the Vietnam War except as symbolic responses to the Pueblo incident and the Tet offensive in 1968.

Indeed, joining the reserves came to be seen during Vietnam as a way to avoid conscription, fulfill the citizenship responsibility of military service, and avoid going to war. The generation now leading most American social institutions remembers the Vietnam role of the reserves as nonwar fighters—rather than the pre-Korea role of major mobilization base—as the norm for American reservist policy.

But military conscription became a casualty of the Vietnam War’s unpopularity, and the decision not to use the reserves was judged by military planners to have been an error. After the end of U.S. military conscription in 1973, the services were reconfigured into a “total force” including both active and reserve components.2 Reserve units, including elements of the National Guard, were mobilized for the first Persian Gulf War, although no National Guard combat brigades actually took part in the relatively short period of combat.

By contrast, nearly 40 percent of the personnel in Operation Iraqi Freedom are from the reserve components, and the figure is not expected to drop below 30 percent on subsequent deployments. An additional 4,000 reserve component soldiers have been sent to the war in Afghanistan. The figure below shows the increase in numbers of reserve personnel on active duty, by branch of service, from October 2001 to December 2003.

Number of National Guard and Reserve Personnel on Active Duty from October 2001 through December 2003, per Month and Year

Source: The 2002 Demographics Profile of the Military Community and The 2003 Demographics Profile of the Military Community (Arlington, Virginia: Military Family Resource Center).

The largest absolute increase during this period was in Army reserve personnel, but the relatively small Marine Corps showed a large relative increase as well, reflecting the centrality of ground combat in the operations in Iraq and Afghanistan. The Navy and Air Force also expanded through the mobilization of reserve personnel, reflecting their roles in the transportation of personnel and equipment to the combat zone as well as in the provision of air support to ground combat troops.

Who Makes Up the Reserves?

The U.S. Department of Defense services are supported by six reserve components: the Army National Guard, the Army Reserve, the Naval Reserve, the Marine Corps Reserve, the Air National Guard, and the Air Force Reserve. The National Guard components evolved from state militia organizations and serve under the command of state governors unless they are federalized. The Army, Navy, Marine Corps, and Air Force Reserves, by contrast, serve only as federalized armed forces. Reserve combat units such as infantry, armor, and fighter squadrons are primarily in the National Guard, while support specialties such as civil affairs are primarily in the federal reserves.

There are three tiers of availability for mobilization within the reserve components. The first tier is the Ready Reserves, which had over 2 million personnel at the advent of the volunteer force in 1973 and now are one-half that size. The Ready Reserves consist of reservists who, within a ceiling set by the Congress, can be called to active duty by the President without congressional consent.

Included in the Ready Reserve are the Selected Ready Reserve, who serve in units, drill periodically, and are paid. Also included are the Individual Ready Reserve/Inactive National Guard (IRR/ING), consisting of trained personnel who have served in but are not currently in units, do not train regularly, and do not get paid, but have a remaining service obligation and are subject to mobilization.

The second tier of availability is the Standby Reserve. As with the IRR, the Standby Reserve have remaining service obligations, do not drill or draw pay, and can only be called to active duty with congressional approval. Finally, the Retired Reserve is the third tier of availability. These reservists have qualified for retirement through length of service or disability and are carried on the reserve roles because military retired pay is legally a compensation for availability rather than a pension. The likelihood of mobilization for these reservists is very low, although the Department of Defense has called for volunteers from the retired reserves to serve in current military operations.

The Army and Air Force Ready Reserves are primarily in Selected Reserve units, and there is no inactive Air National Guard. The Navy’s Ready Reserves are more evenly divided between Selected Reserves and IRR. The Marine Corps’ Ready Reserves are primarily in the IRR.

Women and Minorities in the Reserves

The representation of women has increased in all Selected Reserve components in the last two decades, most dramatically in the federal Selected Reserve forces of the Army, Navy, and Air Force.

Women are less represented in the Army and Air National Guard. Gender integration has been least in the Marine Corps Reserve, the service that also has the smallest proportion of active-duty women. Selected Reserve representation of racial and ethnic minorities (primarily African-Americans and Hispanics) is also high in the Army and Naval Reserve, although minorities account for a greater percentage of the Marine Corps Reserve than of the Air Force Reserve. The Army and Air components of the National Guard are less racially, ethnically, and gender integrated than are the federal reserves.

Will Operation Iraqi Freedom Lead to the Demise of the Reserves?

Operation Iraqi Freedom is redefining the role of the reserves in the U.S. military force structure as radically as did the Vietnam War. The role of the reserve components has been changed from a force in reserve to one of full participation in overseas operations, involving unexpected (and unexpectedly long) deployments. These deployments entail family separations (sometimes repeatedly); “stop-loss” policies that prevent people from leaving service on schedule; reassignments among units; and involuntary occupational reclassifications.

The strain of these deployments and policies has begun to take its toll on the reserves. In the face of discussions about even longer and more frequent call-ups of reservists to support operations in Afghanistan and Iraq, Lt. Gen. Ron Helmly, the chief of the Army Reserve, sent a memo to other Army leaders on Dec. 20, 2004, saying that his force of 200,000 reservists “is rapidly degenerating into a broken force.”3 Thus far in 2005, the Army National Guard is missing its recruiting objectives by one-third, and the Army Reserve is doing only slightly better. Just as the Vietnam War contributed to the end of conscription, the Iraq War may presage the demise—or another major redefinition of the role—of the citizen-soldiers of the reserves.

David R. Segal is Distinguished Scholar-Teacher, professor of sociology, director of the Center for Research on Military Organization, faculty associate in the Maryland Population Research Center, and faculty affiliate in the School of Public Policy at the University of Maryland, College Park. Mady Wechsler Segal is Distinguished Scholar-Teacher, professor of sociology, associate director of the Center for Research on Military Organization, and faculty affiliate in the Women’s Studies Program and in the School of Public Policy at the University of Maryland, College Park. 


  1. Martin Binkin, U.S. Reserve Forces: The Problem of the Weekend Warrior (Washington, DC: Brookings Institution, 1974).
  2. Yuko Kurashina, Meyer Kestnbaum, and David R. Segal, “The Military Participation Ratio (MPR) Update: Mobilization of Non-Active Duty Personnel,” paper presented at the annual meetings of the American Sociological Association, Chicago, August 2004.
  3. Bradley Graham, “General Says Army Reserve is Becoming a Broken Force,” The Washington Post, Jan. 6, 2005.