text: Armies, Corps, and Divisions
  forces, control terrain, protect populations, and preserve joint force freedom of action in the land domain.
  Unified land operations span the entire competition continuum.
  1-56. Army forces conduct decisive action. Decisive action is the continuous, simultaneous execution of
  offensive, defensive, and stability operations or defense support to civil authority tasks (ADP 3-0). The
  simultaneity of decisive action varies by echelon and span of control. The higher the echelon the greater the
  possibility that all elements of decisive action occur simultaneously in its AO. For example, a division, corps,
  or field army always performs some combination of offensive, defensive, and stability operations
  simultaneously. Subordinate brigades and battalions perform some combination of these operations as well,
  but they are generally focused on a specific element of decisive action by their immediate priorities.
  1-57. Unified land operations span the entire competition continuum. Unified land operations address
  combat with armed opponents and the conduct of operations amid populations. This requires Army forces to
  defeat threats while simultaneously shaping civil conditions with unified action partners, which is important
  to campaign success. The relative emphasis on the various elements of decisive action vary with the purpose
  and context of the operations.
  ARMIES, CORPS, AND DIVISIONS IN OPERATIONS
  1-58. The Army maintains and employs armies, corps, and divisions for two reasons. Foremost, they exist
  to prevail in large-scale combat against peer adversaries. Second, they enable political and strategic-level
  leaders to compete effectively against threats in theaters where peer adversaries have demonstrated the
  capability to challenge U.S. strategic interests with military means, above or below the threshold of overt
  armed conflict.
  1-59. Armies, corps, and divisions converge effects from multiple domains, the electromagnetic spectrum,
  and the information environment to achieve a unified purpose. Brigades and lower echelon forces can mass
  effects from the physical domains, but they require significant assistance from higher echelons to converge
  effects from all domains, the electromagnetic spectrum, and the information environment. The ability to
  converge effects is a significant capability that echelons above brigade provide to the joint force.
  1-60. The ability to converge effects rapidly is central to modern operations. First, a peer threat’s ability to
  contest the joint and multinational force in all environments means that Army forces cannot rely on
  capabilities in only a few domains. They must be able to leverage capabilities from across all domains in the
  event that threats are able to secure initial advantages during competition or conflict. Second, by converging
  capabilities from multiple directions and domains, Army forces present threats with multiple interrelated
  dilemmas that are difficult to overcome. These dilemmas can allow the joint and multinational force to offset
  an enemy’s superior numbers or advantages in niche capabilities, seize the initiative, and exploit fleeting
  windows of opportunity to defeat the enemy.
  ROLES OF THE ECHELONS
  1-61. The Army employs theater armies, field armies, corps, and divisions with specific roles and
  responsibilities in support of the Army’s strategic roles. These echelons are foundational to the joint and
  multinational forces’ ability to conduct sustained operations on land because they provide joint force
  commanders (JFCs) capabilities and capacity that exist nowhere else. From a Service perspective, they allow
  the Army to tailor organizations to shape and prevent without sacrificing the Army’s ability to prevail in
  large-scale ground combat and consolidate gains. From a joint perspective, these echelons provide JFCs with
  a range of capabilities and command and control options depending on the mission, operational environment,
  and threat.
  1-62. The way in which an echelon operates depends on its mission, the operational environment, the threat,
  and the type of operation it is supporting. From these considerations, these echelons may perform one of the
  following roles:
  * ASCC.
  * ARFOR.
  * Theater army.
  * Field army.