The Iraq War has been the subject of heated political debate and intense academic scrutiny. Much argument has focused on the decision to invade and the size of the force tasked with the campaign. While these factors have contributed to the challenge of counterinsurgency operations, so has the American approach to unconventional war. Taking full account of the factors beyond the control of the U.S. military and avoiding glib comparisons with Vietnam, this monograph examines how the American approach has affected operations. The author, Dr. Thomas Mockaitis, draws on the experience of other nations, particularly the United Kingdom, to identify broad lessons that might inform the conduct of this and future campaigns. He also documents the process by which soldiers and Marines in Iraq have adapted to the challenging situation and incorporated both historic and contemporary lessons into the new counterinsurgency doctrine contained in Field Manual 3-24