The present study is one of three volumes in a series entitled Challenge and Response in Internal Conflict. The series contains descriptive and analytical accounts covering a total of 57 cases of insurgency and counterinsurgency occurring in the 20th century. The three volumes are individually entitled The Experience in Asia (19 cases), The Experience in Europe and the Middle East (18 cases), and The Experience in Africa and Latin America (20 cases). The purpose of the project was to enlarge the body of knowledge about insurgency and especially counterinsurgency by empirical study of actual historical cases. From a sample of about 150 cases, 57 were selected according to criteria governing time, definition, occurrence of military operations, analogy, and feasibility. Persons of academic and professional background were then selected to study individual cases according to a standardized methodology (described in the Technical Appendix). The individual studies were written in a format covering background, insurgency, counterinsurgency, and outcome and conclusions, followed by notes and bibliographic material. The studies have been grouped geographically in three volumes to form casebooks on the subject of internal conflict. In addition, the cases now published plus some further materials collected during their preparation form a data bank for the further analysis of insurgency and counterinsurgency.

The paper evaluates current knowledge about the nature of internal war and the types of research being undertaken to increase this knowledge. There were 380 conflicts in the world in the 19 years following World War 2, involving 81 percent of the 123 independent countries in the world. During this period, there were from 13 to 30 new conflicts each year and an average of 13.6 on-going conflicts each month, but there was no formal declaration of war in any conflict. The crucial conceptual issues about internal war are still in the pretheoretical stage. New research on internal war should examine the interaction of the antagonists on a time-line basis, utilize reliable attitudinal data, and examine what happens after hostilities are over, since the real impact of a revolution seems to occur after rather than during the period of active combat. (Author).