There is little need for extended comment on the sources used in preparing this volume. Their nature will be evident in the footnote citations. With the exception of a few passages, and these largely in the first chapters, the entire work is based on primary sources. These consist of the official records of the United States and United Nations armed forces bearing on the land, sea, and air action. ROK records were also consulted, but generally they were scant and sometimes nonexistent.
The U.S. Army ground organizations kept war diaries from army level down through infantry regiments and artillery and tank battalions. They also maintained daily periodic intelligence and operations reports and journal message files. Separate battalions kept similar records. Although not required by the Adjutant General for record purposes, infantry battalion war diaries in some instances were attached to regimental war diaries and in that manner found their way into the permanent records of the Department of the Army. Included in the daily Eighth Army War Diary was a useful G-3 Air report.
Some contemporary army records were lost in combat. The most important of these were the records of the 34th Infantry Regiment, lost in the battle of Taejon in July 1950, and the records of the 2d Infantry Division and of its 9th and 38th Regiments, lost at Kunu-ri in late November 1950. Substitutes were made up from memory of individuals and scattered sources bearing on the period. The records of the sth Regimental Combat Team for its first month of combat, August 1950, were never located, although a thorough search for them was made in the Adjutant General's Office.
The Marine combat units kept records called special action reports that were similar to the Army war diaries, together with annexes covering subordinate units and staff sections. They also maintained G-2 and G-3 journal files.
For the Inch'on landing and the Wonsan-Hungnam operation, the naval records of Joint Tasl; Force Seven were indispensable sources.
All the war diaries, special action reports, periodic reports, and journal files of combat units and headquarters at all levels were read and studied, as well as similar reports of logistical and service organizations.
Supplementing the records, and often more important, as indicated in the Preface, were the firsthand accounts of participants. These have come from army commanders, corps and division cornmanders, regimental and battalion commanders, company commanders, platoon leaders, staff officers, platoon sergeants, other noncommissioned officers, and privates in personal interviews, correspondence, and their review of early manuscript drafts on actions in which they fought. Each such personal account was checked against the others and the
records, and all were used in the framework of the time sequence and map locations given in the operations journals and periodic reports of the various command echelons. Discrepancies abounded. Often it was not easy to reconcile conflicting evidence and arrive at a narrative in which one could have confidence.
Enemy sources used consisted of captured North Korean and Chinese Communist Forces documents and thousands of reports of interrogations of prisoners from both the North Korean Army and the Chinese Communist Forces. The value of the interrogation reports varied widely depending upon the rank and position in the enemy organization held by the prisoner. Many were entirely valueless, but one could never know in advance what little scrap of information any report might yield. The most useful body of enemy material was in the collections of the Allied Translator and Interpreter Section (ATIS) of General MacArthur's Far East Headquarters, although a sizable amount of similar material was included as attachments to the S-2 and G-2 periodic reports of regiments, divisions, corps, and army. Interrogation of prisoner reports found with the records of combat units had a particular value because they often represented the best information available to the troops on the enemy situation in their immediate front, although later interrogation reports might be more complete.
The writer believes that good military history cannot be written without a clear knowledge of the terrain involved in action. He studied the terrain on the ground itself whenever possible, and gave to map study a proportionately large allotment of time. The Army Map Service map of Korea, scale 1:50,000, fourth edition, February 1951, was the standard terrain map used, although earlier editions and maps at both larger and smaller scales were also consulted. Special maps were employed in the case of actions involving towns and cities of any size.