text: Chapter2
  echelon with their proximity to the current situation at the point of execution. While higher echelons provide
  broad perspective, subordinate echelons provide tactical fidelity. Combining the higher echelon perspective
  with the perspectives of subordinates creates the shared situational understanding that fosters disciplined
  initiative. Shared situational understanding does not require all leaders to agree. Instead, leaders use
  differences of opinion to frame the problem, assess operations, understand risk, and guide information
  collection.
  The focus of echelons changes across strategic contexts as do their responsibilities for integrating
  multidomain capabilities into operations. Their broad roles are listed in paragraphs 2-79through 2-94. (See
  Chapters 4, 5, and 6for descriptions of each strategic context and more detailed information on echelon roles
  and responsibilities.)
  Theater Army
  The theater army’s mission is the most diverse and complex of any Army echelon. The theater army
  headquarters is tailored to a specific CCDR with the ability to conduct both operational and administrative
  C2 over Army forces theater wide. It provides enabling capabilities appropriate to theater conditions, such as
  theater intelligence, theater sustainment, theater signal, theater fires, theater information activities, civil
  affairs, engineer, and theater medical. In theaters without assigned field armies, corps, or divisions, the theater
  army assumes directresponsibility across warfighting functions for its tactical commands. The theater army
  is the Army Service component command to a geographic combatant command. The seven functions
  performed as the Army Service component command are—
  (cid:122) Execute the CCDR’s daily operational requirements.
  (cid:122) Provide administrative control (ADCON) of Army forces.
  (cid:122) Set and maintain the theater.
  (cid:122) Set and support operational areas.
  (cid:122) Exercise C2 of Army forces in the theater.
  (cid:122) Perform joint roles of limited scope, scale, and duration.
  (cid:122) Plan and coordinate for the consolidation of gains in support of joint operations.
  (See FM 3-94 and ATP 3-93 for additional information on theater army administrative and operational
  requirements.)
  Field Army
  A field army is constituted to meet specific requirements. A field army may consist of a headquarters
  battalion with subordinate companies and special troops, a variable number of attached corps, an attached
  expeditionary sustainment command, a variable number of divisions normally attached to corps, and other
  attached functional and multifunctional brigades.
  When required, a field army is an operational headquarters that provides C2 over multiple corps.
  During operations, forces are assigned or attached to the field army. Although it may employ subordinate
  units during operations, these units are provided by external Army, joint, and multinational sources based on
  the situation and the field army’s role and mission. When constituted, a field army is tailored to mission
  requirements and designed to perform operational ARFOR tasks; it is the Army component to the JFC to
  which it is assigned.
  The field army provides additional operational capacity to a CCDR facing peer adversaries in its AOR.
  The field army is tailored based on the capabilities of the peer adversary. As the adversary’s capabilities
  change, so do those of the field army. When constituted, the field army provides Army, joint, and
  multinational forces with a headquarters capable of performing in a variety of ways across the range of
  military operations. Field armies are most likely to be employed in theaters where peer adversaries have the
  capability of conducting large-scale combat. These regions include the U.S. European Command and U.S.
  Indo-Pacific Command.