Corps area
A corps area was a geographically-based organizational structure (military district) of the United States Army used to accomplish administrative, training, and tactical tasks from 1920 to 1942.Each corps area included divisions of the Regular Army, Organized Reserve, and National Guard of the United States.The First, Second, Third, Fourth, Eighth, and Ninth Corps Areas also organized units to man various fixed coastal defenses.For the century preceding 1920 the U.S. Army was geographically divided into series of Military Divisions, "Departments" and smaller "Districts" and Subdistricts.The corps areas were formed for administration, training, and tactical control of the army, replacing the six geographical (or territorial) military departments into which the continental United States had been divided since 1917 and with little variation since the Civil War.[1] The 1920 act was a realization that the mobilization of a citizen army could no longer meet the defense needs of the United States and for the first time placed an emphasis on peacetime preparedness.The act authorized the establishing new schools to meet modern military educational needs, such as the Army Industrial College in 1924.During times of civil unrest, labor strikes, or natural disasters, corps area commanders provided Army resources needed to address the emergency.The higher numbered corps (XI through XIX) each consisted of three divisions, also assigned by state boundaries, of the newly established (but rarely funded) Organized Reserve.Corps areas were then limited to their Zone of the Interior functions as service commands and the field armies assumed control of all tactical units.
military districtUnited States ArmyRegular ArmyOrganized ReserveNational Guard of the United StatesmobilizationWorld War IGreat DepressionUnited States War DepartmentDepartmentsZone of the InteriorReserve Officers Training CorpsCitizens Military Training Campfield armyCommunications Zone"Departments"DistrictsWar of 1812National Defense Act of 1916Hawaiian DepartmentPanama Canal DepartmentPhilippine DepartmentCommand and General Staff SchoolFort LeavenworthArmy War CollegeCarlisle BarracksArmy Industrial Collegedivisioncivil unrestlabor strikesnatural disasters"type" corpsNational GuardCoolidge AdministrationarmiesFort JayGovernors IslandFirst Corps AreaFirst United States ArmyEastern DepartmentUnited States First ArmyII Corps (United States)1st Infantry Division27th Infantry Division44th Infantry DivisionXII Corps (United States)77th DivisionOrganized Reserves21st Cavalry Division (United States)61st Cavalry DivisionFort McHenryFort HowardXIII Army Corps99th Divisions62nd Cavalry Division2d Observation WingWashington D.C.14th Aero Squadron9th Bombardment GroupWalter S. GrantFourth Corps Area4th DivisionFifth Corps AreaFort Benjamin HarrisonFort HayesColumbus, OhioSecond100th Infantry DivisionsSixth Corps AreaJefferson BarracksFort SheridanU.S. Post Office6th Division23rd Cavalry Division (United States)Seventh Corps AreaFort Crook, NebraskaEighth Corps AreaFort Sam HoustonSan Antonio44th Observation Squadron154th Observation SquadronFrank M. AndrewsGHQ Air ForceBilly MitchellFranklin D. RooseveltGeorge C. MarshallChief of Staff of the United States ArmyMalin CraigPresidio of San FranciscoWestern Department41st Division18th Squadron (Observation)19th Squadron (Pursuit)7th Bombardment Group17th Attack GroupMarch Field1st Bombardment Wing91st Observation SquadronCivilian Conservation CorpsDouglas MacArthurArmy Ground ForcesEasternCentralSouthernWesternServices of SupplyArmy Service ForcesEastern Defense CommandCentral Defense CommandSouthern Defense CommandWestern Defense CommandGeorge MarshallAlexander M. PatchFirst ArmySecond Service CommandSecond ArmyThird Service CommandThird ArmyFort McPhersonFourth Service CommandFourth ArmyFifth ArmySixth Service CommandSixth ArmyFirst Service CommandFifth Service Command