This counterinsurgency field manual is designed to fill a gap within the doctrine of how the U.S. Military fights its wars. It has been 20 years since the Army published a field manual devoted exclusively to counterinsurgency operations. For the Marine Corps it has been 25 years. With U.S. Soldiers and Marines fighting insurgents in Afghanistan and Iraq, it is essential that they are given a manual that provides principles and guidelines for counterinsurgency operations. Such guidance must be grounded in historical studies. However, it also must be informed by contemporary experiences. This is an important document that is now available for the layman and the student of military strategy in addition to the professional U.S. Soldier and Marine.