During its campaigns across Europe in World War II, the Army had assigned historians to the field for close-up documentation of recent actions through participant interviews. The value of their work was soon proven in both official and independently researched histories. Having eyewitnesses from all ranks recall their experiences just after the event gave a new dimension to military history. Beginning in early 1951, a similar effort was launched in Korea, although now the interviews, recorded in summaries, were used as a basis for narrative and analytical reports by the historians. Some of these reports were designated after-action reports, focusing closely on small units in detail. Others-the studies-reviewed broad aspects of the war effort and thus were not limited to the actions of a particular unit. Many of these were completed in Japan after the fighting had ended and fuller documentation from paper records was available to supplement the interviews.