text: Chapter 3
  Multi-Corps Command and Control in Korea, 1950
  When North Korea invaded South Korea in June 1950, the conflict found the U.S.
  military unprepared to operate in a major land war in East Asia. Those few U.S. Army
  elements in Japan and elsewhere in the region had only recently shifted focus from
  constabulary operations to preparing for large-scale combat operations. Furthermore,
  the Far Eastern Command, then commanded by General Douglas MacArthur, began
  the conflict without a suitable operational-level headquarters to command and control
  multiple corps and divisions in the land domain. Faced with the immediate requirement
  to establish a flexible command and control architecture for the emerging Korean
  theater, MacArthur selected the Eighth U.S. Army in Japan to be the land component
  command.
  Eighth Army had only recently shifted its focus from its constabulary mission in Japan
  to training for potential large-scale combat operations. Its commander, General Walton
  H. Walker, led a small staff that directly supervised four undermanned and
  underequipped infantry divisions because its two subordinate corps headquarters had
  been eliminated as the U.S. military downsized following victory in World War II. After
  designating Eighth Army as the land component command in Korea, MacArthur
  assigned it the additional responsibility of commanding five allied South Korean
  divisions. As a further complication, Walker maintained responsibility for directing
  logistic operations in Japan even as his headquarters assumed responsibility for
  combat operations on the Korean Peninsula.
  Senior military leaders recognized Eighth Army’s command and control challenges and
  gradually addressed issues stemming from the improvised command arrangement. To
  expand Walker’s staff, the Army carefully selected experienced officers for key
  positions. In August 1950, MacArthur alleviated the responsibility for logistic duties in
  Japan from Walker by assigning them to the new Japan Logistical Command. Most
  importantly, the U.S. Army activated the I and IX Corps headquarters to control
  divisions for Eighth Army. In July 1950, MacArthur had demanded these echelons,
  recognizing that Walker was at the time commanding nine divisions—which exceeded
  his headquarters’ span of control. While the combat force in Korea required further
  improvement, these additions began the critical process of creating a field army
  capable of directing multinational corps towards achievement of strategic aims.
  THE ROLE OF THE FIELD ARMY
  3-125. When constituted, the field army’s role is to serve as the ARFOR in a subordinate AO. Army doctrine
  distinguishes between the ARFOR of a combatant command and that of a joint force formed by the combatant
  commander. The ASCC of the combatant command is the ARFOR for the theater and the Army component
  of the subordinate joint force, the field army is the ARFOR for multi-corps operations in the subordinate AO.
  The ASCC as the ARFOR maintains control of all Army units in an AOR until such time that control is
  passed to the field army. As part of controlling Army forces, the ARFOR maintains ADCON of Army forces,
  and it addresses service responsibilities such as coordinating ASOS. (See Appendix B of this manual for
  more information on the ARFOR.)
  3-126. Field armies may execute competition-related tasks as directed by the theater army. However, they
  primarily facilitate the transition to armed conflict by focusing on activities that must occur in an AO. This
  allows the theater army to maintain its AOR-wide orientation as the ASCC. As the ARFOR, the field army
  performs seven functions:
  * Execute command and control over multi-corps operations. (See paragraph 3-127.)
  * Execute ADCON in the AO. (See paragraph 3-128.)