text: Armies, Corps, and Divisions
  Theater Army
  1-69. A theater army is an echelon of command
  designated as the Army Service component Army executive agent responsibilities
  command responsible for recommendations of Under the authority of the Secretary of Defense and
  allocation and employment of Army forces to the 10 USC, the Army has been designated the
  geographic combatant commander (JP 3-31). The executive agent by the Secretary of Defense or
  Deputy Secretary of Defense for foundational
  theater army is organized, manned, and equipped to
  activities that are not necessarily landpower
  perform four roles:
  equities, but functions necessary to the entire joint
  * ASCC for the GCC to which it is force. These functions include, but are not limited
  assigned. This is its primary role. to—
  * JTF headquarters (with augmentation)  DOD detainee operations policy.
  for a limited contingency operation in  DOD Biometrics and Forensics.
  that AOR.
   Armed Services Blood Program Office.
  * Joint force land component (with
   Chemical and biological defense program.
  augmentation) for a limited contingency
   Chemical demilitarization.
  operation in that AOR.
  * Theater joint force land component  DOD Combat Feeding Research and
  Engineering Program.
  (with augmentation) when designated
  by the GCC.  DefenseLanguageInstituteForeignLanguage
  Center.
  1-70. The theater army is responsible to the Department of the Army for Service-specific requirements.
   DODLevelIIIcorrections.
  Through the theater army, the Department of the Army provides certain support to other Services through
   Explosivessafetymanagement.
  several types of authorities. These are known collectively asArmy supportto otherServices (ASOS). The
  GCC may designate the Army to serve as the lead Service and provide common-user logistics for the entire
  theater, areas within a theater, or specific joint operations.
  1-71. The theater army always maintains an AOR-wide (theater) focus, providing support to Army and joint
  forces across the region, in accordance with the GCC’s priorities of support. Depending on the region and
  the GCC’s priorities, the relative emphasis that the theater army places on its operational and administrative
  responsibilities can vary greatly. However, the theater army’s operational requirements are generally greatest
  during competition, the transition from competition to armed conflict, and the transition from armed conflict
  back to competition. This is because the Army usually introduces other echelons into an AOR to relieve the
  theater army’s operational burden in a potential or actual operational area when conflict is possible or likely.
  This allows the theater army to focus on its Title 10, USC duties that support the theater during armed conflict.
  It also frees the theater army to perform tasks that no other Army echelon can accomplish during armed
  conflict: shaping the theater to improve the relative positions of advantage that the United States and its allies
  enjoy, protecting against threat actions outside of an operational area, and preventing the unintended
  expansion of conflict by friendly decision makers and senior commanders. However, theater army
  commanders and staffs also play an important operational function during large-scale combat by detecting
  and striking enemy capabilities that reside in the theater but outside of an operational area.
  1-72. In its role as the ASCC, the theater army executes operational and administrative responsibilities. (See
  Chapter 3 for additional information on the theater army. See ATP 3-93 for additional information on
  operational and administrative responsibilities.)
  Field Army
  1-73. A field army is an echelon of command that employs multiple corps, divisions, multifunctional
  brigades, and functional brigades to achieve objectives on land (JP 3-31). The field army, when established,
  is simply a headquarters. Although it employs subordinate units during the course of operations, these units
  are provided by external Army, joint, and multinational sources based on the situation, the field army’s role,
  and its mission. When established, the field army will be manned and equipped to perform two roles:
  * An ARFOR (with significant augmentation) in a joint force for campaigns and major operations.
  * A JFLCC (with augmentation) commanding multiple U.S. and multinational corps as well as
  Marine Corps forces together with supporting brigades and commands.