text: Chapter 3
  Armies
  A war should only be undertaken with forces proportioned to the obstacles to be overcome.
  Napoleon
  This chapter provides an overview of the theater and field armies. The chapter is
  divided into two sections. Section I describes the roles, functions and tasks of the
  theater army. The section concludes with a description of the theater army’s
  organization and limitations. Section II describes the roles, functions and tasks of the
  field army. Section two concludes by describing the field army’s limitations.
  ARMIES OVERVIEW
  3-1. An army is organized with multiple echelons, each of which can be task-organized with an appropriate
  mix of capabilities and sizes to perform specific roles. Each echelon commands and controls a number of
  subordinate functional and multifunctional units, employing them in a coherent, coordinated, and
  synchronized fashion to achieve its objectives. The higher echelon ensures unity of purpose, directing and
  orchestrating the individual subordinate units to achieve success.
  3-2. The theater and field army (when constituted) are the two senior Army echelons available to a GCC.
  They provide the GCCs flexibility in employing land power as well as planning and coordinating for the
  consolidation of gains in support of joint operations. Both echelons command and control multiple
  subordinate echelons as they execute operations across the competition continuum.
  SECTION I – THEATER ARMY
  The nature of armies is determined by the nature of the civilization in which they exist.
  B.H. Lindell Hart
  3-3. The theater army consists of a headquarters and all assigned or attached Army forces in the AOR not
  assigned or attached to a subordinate joint force of the geographic combatant command. Each theater army
  provides its respective GCC with capabilities and support in the form of landpower. When properly
  augmented and directed, an element of the theater army headquarters can assume the role of a JTF
  headquarters or joint force land component command.
  3-4. The theater army is optimized to meet the requirements of their AOR based upon available Army
  resources. Theater armies are culturally aware and continuously involved with their security cooperation
  partners in the region. Even when it supports large-scale combat in an operational area, the theater army
  retains the responsibility to shape the operational environment, prevent additional conflict, and consolidate
  gains elsewhere in theater. When other Army echelons are committed to the AOR it must remain focused on
  shaping the theater-wide environment while setting the theater to support operations in JOAs. No other Army
  echelon headquarters is capable of fulfilling that requirement. The theater army must maintain its AOR-wide
  focus to be able to fulfill its Service and ASOS responsibilities while continuing to provide support to specific
  joint operations with JOAs.
  3-5. The theater army’s mission is one of the most diverse and complex of any Army echelon. The
  headquarters is tailored to a specific GCC AOR with the ability to conduct both operational and
  administrative command and control over Army forces theater-wide. It also provides enabling capabilities
  appropriate to theater conditions such as theater casualty evacuation, theater signal, theater sustainment, and
  theater intelligence. In theaters without assigned field armies, corps, or divisions, the theater army must