The U.S. Army and Irregular Warfare, 1775-2007, edited by Richard G. Davis, publishes fifteen papers read in August 2007 at the sixteenth Conference of Army Historians, a biennial history conference attended by members of the Army Historical Program, academics from leading colleges and universities, and international scholars from allied nations. The papers selected for this publication are not only the best of those presented, but they also examine irregular warfare in a wide and diverse range of circumstances and eras. Together, they demonstrate how extremism was intimately connected to this type of warfare and how Americans have, at different times in their history, found themselves acting as insurgents, counterinsurgents, or both. The titles of the papers themselves reflect how often the U.S. Army has engaged in such irregular operations despite a formal focus on conventional warfare. Using imperial British and Italian examples, several presentations also underline how the ease of conquering lands is often no indication of the level of effort required to pacify them and integrate them into a larger whole.