Book excerpt: "Military History Operations," (ATP 1-20 / FM 1-20) is applicable to all Army military history offices, military history units, and military history operations of major tactical and support commands generally at corps level and below. FM 1-20 provides basic doctrine describing the roles, relationships, organizations, and responsibilities of Army component command historians, historians, unit historical officers, and military history detachment (MHD) members in the United States Army. It describes, but does not extensively cover, historians and historical offices of units at echelons above corps and at the joint level. It is designed to provide historians, unit historical officers, commanders, and staffs the methods to preserve and document the history of the U.S. Army. It explains how the Army conducts military history operations during wartime, for both deployed forces in the combat theater and those units supporting the operation. The Army has responded to numerous contingencies or military operations other than war in recent years, and this FM provides doctrine on conducting military history operations during such contingencies. It also provides commanders doctrinal guidance on the employment of organic military history assets as well as separate military history units.