Book excerpt: American Military History provides the United States Army-in particular, its young officers, NCOs, and cadets-with a comprehensive but brief account of its past. The Center of Military History first published this work in 1956 as a textbook for senior ROTC courses. Since then it has gone through a number of updates and revisions, but the primary intent has remained the same. Support for military history education has always been a principal mission of the Center, and this new edition of an invaluable history furthers that purpose. The history of an active organization tends to expand rapidly as the organization grows larger and more complex. The period since the Vietnam War, at which point the most recent edition ended, has been a significant one for the Army, a busy period of expanding roles and missions and of fundamental organizational changes. In particular, the explosion of missions and deployments since 11 September 2001 has necessitated the creation of additional, open-ended chapters in the story of the U.S. Army in action. This first volume covers the Army's history from its birth in 1775 to the eve of World War I. By 1917, the United States was already a world power. The Army had sent large expeditionary forces beyond the American hemisphere, and at the beginning of the new century Secretary of War Elihu Root had proposed changes and reforms that within a generation would shape the Army of the future. But world war-global war-was still to come. The second volume of this new edition will take up that story and extend it into the twenty-first century and the early years of the war on terrorism and includes an analysis of the wars in Afghanistan and Iraq up to January 2009.