+------+
+-----------+CinCFE+-------------+
| +------+ |
+---+----+ +----+-----+
+----+ComNavFe+--------+ |CG X Corps|
| +--------+ | +----------+
| |
+------+-------+ +------+------+
|ComPhibGru One| |CG 1st MarDiv|
+--------------+ +-------------+
All the top commanders were concentrated in Tokyo with the arrival of Admiral Struble on 25 August. This facilitated the planning and allowed important decisions to be worked out in conferences between the principal commanders.[88]
[88] Struble ltr, 25 Apr 55.
Planning was based mainly on studies made by ComPhibGru One as prospective Attack Force Commander. It was conducted entirely on a concurrent basis by the Attack Force and Landing Force groups aboard the Mount McKinley. No step was taken by either without the full knowledge and consent of the other.
X Corps Scheme of Maneuver
Army planning had been initiated by the Joint Strategic Plans and Operations Group until 16 August, when the “Special Planning Staff” was set up at GHQ to issue directives for Operation Plan CHROMITE. Published on 12 August as CinCFE Operation Plan No. 100-B, it was based on these assumptions:
| (a) | that the North Korean ground advance would be stopped in time to permit the build-up of our forces in South Korea; |
| (b) | that our forces in South Korea would be built up to the capability of mounting effective offensive operations against NKPA forces opposing them; |
| (c) | that we retain air and naval supremacy in the area of operation; |
| (d) | that the NKPA ground forces would not receive major reinforcements from the USSR or Red China; |
| (e) | that there would be no major change in the basic disposition of the NKPA forces.[89] |
[89] MarCorps Board Study, v. II-B, 13–17.
It was understood from the beginning that the Special Plans Staff, headed by General Ruffner, would be the nucleus of the future X Corps staff. In order to have the benefit of specialized amphibious knowledge, ten Marine and two Navy officers of TTU Mobile Training Team Able were assigned on 19 August:
| Col H. A. Forney | Deputy Chief of Staff |
| LtCol J. Tabor | Asst Coordinator, FSCC |
| LtCol C. E. Warren | Asst G-4 |
| Maj J. N. McLaughlin | Asst G-3 |
| Maj J. F. Warner | Asst G-3 |
| Maj C. P. Weiland | Air Officer, FSCC |
| Maj V. H. Vogel | Asst G-4 |
| Capt H. S. Coppedge | Asst G-2 |
| Capt T. A. Manion | Asst Signal Officer, FSCC |
| Capt V. J. Robinson | Target Info Officer |
| Lt L. N. Lay, USN | Asst Surgeon |
| Lt W. A. Sheltren, USN | Asst NGF Officer, FSCC[90] |