United States Army Reserve

The United States Army Reserve, commonly abbreviated USAR, is the federal reserve component of the United States Army. It provides trained soldiers and specialized units that can reinforce the active Army during war, national emergencies, contingency operations, and other missions directed by the federal government. Together with the Army National Guard, it forms the reserve component of the Army, although the two organizations differ in legal status and command relationships. The Army Reserve is a federal force, while the Army National Guard normally operates under state authority until called into federal service. The institution traces its official lineage to the creation of the Medical Reserve Corps by Congress on 23 April 1908. Following the First World War, the National Defense Act of 1920 reorganized the Army’s reserve structure by authorizing a Regular Army, a National Guard, and an Organized Reserve. The Organized Reserve incorporated the Officers Reserve Corps and Enlisted Reserve Corps, along with related reserve arrangements and the Reserve Officers’ Training Corps pipeline. Its purpose was to maintain a pool of trained personnel and partially organized units that could be expanded and mobilized in an emergency. During the interwar years, the Organized Reserve maintained divisions and supporting units across the United States, including infantry, artillery, cavalry, engineer, medical, signal, quartermaster, and ordnance formations. In practice, limited funding, inadequate facilities, low drill compensation, and irregular access to training restricted readiness. Many units existed primarily as cadres of officers, while enlisted strength was often comparatively small. The system also struggled to balance two objectives: preparing complete reserve formations for rapid employment and maintaining a broad pool of personnel for expansion of the Army during a major mobilization. The approach changed sharply before and during the Second World War. Beginning in 1940, Reserve officers were called to active duty individually and assigned to Regular Army and National Guard formations. Their numbers grew substantially as the Army expanded. Executive Order 9049, signed by President Franklin D. Roosevelt on 6 February 1942, ordered Organized Reserve units and personnel not already serving to active duty for the duration of the war and six months afterward. Because many Reserve officers had already been mobilized, the wartime units often differed considerably from their peacetime organization and personnel. After the war, the reserve system was rebuilt and repeatedly reorganized. The Organized Reserve Corps was redesignated on 25 March 1948, and Congress authorized retirement and drill pay for the first time that year. Postwar plans initially contemplated a large structure containing armored, airborne, and infantry divisions. Readiness problems, the cost of maintaining major formations, changing mobilization requirements, and the experience of the Korean War led to further redesignations and reductions. Several divisions were converted to infantry formations, while others became training or maneuver-area organizations intended to support mobilization rather than function as fully manned combat divisions. Over time, the Army Reserve increasingly emphasized specialized capabilities, including medical, logistical, transportation, engineering, civil affairs, military police, information, and other support functions. Its personnel generally serve part time while maintaining civilian careers or studies, but they can be placed on active duty under federal authority. Army Reserve soldiers have supported major operations and domestic emergency responses across the modern era, including missions associated with the post-September 11 conflicts, humanitarian assistance, disaster response, medical support, logistics, and homeland missions. The Army Reserve is therefore not a commercial brand or a conventional service provider. Its identi…

The Army Reserve’s institutional origins lie in the early twentieth-century effort to create a trained federal manpower pool without maintaining a permanently large standing Army. Congress established the Medical Reserve Corps on 23 April 1908. This organization provided the immediate official predecessor to the later Army Reserve and reflected the Army’s need for professionally trained medical personnel who could be called upon during national emergencies. The National Defense Act of 1920 created the framework that became the Organized Reserve. It placed the reserve structure alongside the Regular Army and the National Guard and authorized both an Officers Reserve Corps and an Enlisted Reserve Corps. The Organized Reserve also operated in conjunction with ROTC and other training programs that supplied potential officers and technically qualified personnel. Its peacetime role was to maintain a reservoir of trained people and partially organized units that could be expanded during war. In the 1920s and 1930s, the Organized Reserve maintained divisional lineages and a wide range of supporting formations. Infantry divisions generally retained geographic associations with First World War units, while artillery, coast artillery, cavalry, engineers, medical, signal, quartermaster, and ordnance units provided additional capabilities. Some Regular Army units in inactive status were affiliated with ROTC institutions, allowing Reserve officers and college-based military programs to sustain organizational connections. By the early 1930s, ROTC graduates represented an important source of Reserve officers. The interwar system was constrained by money, facilities, and participation. Inactive training drills were generally unpaid, and opportunities for paid annual training were irregular. Many units had enough officers on paper but very few enlisted members. The Enlisted Reserve Corps also had restrictive entry requirements, which limited its size. These weaknesses produced continuing uncertainty about whether the reserve should be organized mainly as a source of individual replacements and officers or as a force of nearly complete units ready for mobilization. That uncertainty was overtaken by the rapid expansion of the Army before the United States entered the Second World War. Reserve officers were called to active duty individually from 1940 onward and assigned to Regular Army units and, after National Guard mobilization, to Guard units. The number of Reserve officers on active duty rose from 2,710 on 30 June 1940 to more than 46,000 by 15 May 1941, and reached approximately 80,000 by December 1941. Executive Order 9049, issued on 6 February 1942, formally ordered the remaining Organized Reserve organizations and personnel into active military service for the war and a postwar period. In practice, wartime units often bore limited resemblance to their prewar Reserve versions because their officers and personnel had already been redistributed during mobilization. Postwar planners sought to rebuild the Organized Reserve as a substantial force. A 1946 troop basis proposed twenty-five divisions in armored, airborne, and infantry categories. The planned formations were organized between 1946 and 1947, although the final composition differed from the initial proposal. The Organized Reserve Corps was redesignated on 25 March 1948, and legislation that year introduced retirement and drill pay, helping establish a more sustainable reserve-service model. The Korean War era exposed continuing difficulties in manning, equipping, housing, and training large Reserve divisions. During the early 1950s, Army leaders reduced and reorganized the divisional structure. Several armored and airborne divisions were converted into infantry divisions, while other formations were transformed into training divisions, replacement-training centers, or maneuver-area commands. These changes reflected the judgment that the reserve could provide greater practical value by supporting mobilization and training than by maintaining numerous nominally complete combat divisions with insufficient resources. The later history of the Army Reserve was characterized by a shift toward specialized and enabling functions. Rather than serving principally as a second-line collection of traditional combat divisions, the force developed extensive medical, transportation, logistics, engineering, civil-affairs, military-police, communications, and other support capabilities. The part-time status of most soldiers allowed the federal government to retain expertise and manpower at lower permanent cost while drawing on civilian skills and regional recruiting networks. In the post-Cold War and post-September 11 periods, Army Reserve units and personnel became recurring participants in overseas contingency operations, homeland missions, humanitarian assistance, medical support, logistics, and disaster response. The organization continues to function as a federal reserve force whose soldiers may serve in a normal part-time status, conduct recurring training, or be ordered to active duty when national requirements demand. Its modern role is consequently defined less by a fixed divisional order of battle than by readiness, mobilization depth, and specialized support to the broader United States Army.

• 1955

  Reserve divisions converted to training and maneuver organizations

  [1]United States Army Reserveen.wikipedia.org

  A number of divisions were reorganized as cadres for replacement-training centers or as maneuver-area commands, reflecting a revised mobilization concept.

• 1952

  Airborne and armored divisions reorganized

  [1]United States Army Reserveen.wikipedia.org

  Several Army Reserve airborne and armored divisions were reorganized and redesignated as infantry divisions as part of post-Korean War restructuring.

• 1948

  Organized Reserve Corps redesignated and pay authorized

  [1]United States Army Reserveen.wikipedia.org

  The Organized Reserve Corps designation was adopted on 25 March 1948, and Congress authorized retirement and drill pay for Reserve service.

• 1942

  Executive Order 9049 mobilizes the Organized Reserve

  [1]United States Army Reserveen.wikipedia.org

  President Franklin D. Roosevelt ordered Organized Reserve organizations and personnel not already serving into active military service for the duration of the war and six months afterward.

• 1940

  Large-scale mobilization of Reserve officers begins

  [1]United States Army Reserveen.wikipedia.org

  The Army began calling substantial numbers of Reserve officers to active duty and assigning them to expanding Regular Army and National Guard formations.

• 1920

  National Defense Act reorganizes the reserve system

  [1]United States Army Reserveen.wikipedia.org

  The National Defense Act created the postwar framework of a Regular Army, National Guard, and Organized Reserve, including officer and enlisted reserve components.

• 1908

  Medical Reserve Corps established

  [1]United States Army Reserveen.wikipedia.org

  Congress created the Medical Reserve Corps on 23 April 1908, establishing the official predecessor of the Army Reserve.

A federally controlled citizen-soldier force that expands the capacity of the United States Army and supplies specialized capabilities for national defense, contingency operations, and emergency response.

• Military manpower · 1908

  Federal reserve service

  The Army Reserve maintains soldiers in a trained federal reserve status. Most serve part time while pursuing civilian employment or education, but they remain subject to federal activation and can reinforce the active Army during war, national emergencies, and contingency operations.

• Military healthcare · 1908

  Medical support

  Medical capability is central to the Army Reserve’s historical lineage, which began with the Medical Reserve Corps. Modern Reserve medical formations provide personnel and organizational support for military healthcare, casualty care, evacuation, public-health activities, and emergency response when mobilized.

• Military logistics

  Logistics and transportation

  Reserve logistics and transportation units help move personnel, equipment, fuel, supplies, and other materiel. These capabilities support expeditionary operations and provide surge capacity during large mobilizations, when the active Army requires additional sustainment infrastructure.

• Military engineering

  Engineering and construction

  Army Reserve engineering formations provide construction, infrastructure, route, utilities, and related technical capabilities. Their missions can support deployed forces, base operations, disaster response, and other federal requirements requiring specialized engineering manpower.

• Operational support

  Civil affairs and specialized support

  The Army Reserve supplies specialized units such as civil-affairs, military-police, communications, and other enabling formations. These organizations connect military operations with civilian environments and provide capabilities that are difficult to maintain solely through the active component.

1. 1United States Army Reserveen.wikipedia.org
2. 2Official United States Army Reserve websiteusar.army.mil