World War II was the largest and most violent armed conflict in the history of mankind. However, the half century that now separates us from that conflict has exacted its toll on our collective knowledge. While World War II continues to absorb the interest of military scholars and historians, as well as its veterans, a generation of Americans has grown to maturity largely unaware of the political, social, and military implications of a war that, more than any other, united us as a people with a common purpose. Highly relevant today, World War II has much to teach us, not only about the profession of arms, but also about military preparedness, global strategy, and combined operations in the coalition war against fascism. During the next several years, the U.S. Army will participate in the nation's 50th anniversary commemoration of World War II. The commemoration will include the publication of various materials to help educate Americans about that war. The works produced will provide great opportunities to learn about and renew pride in an Army that fought so magnificently in what has been called "the mighty endeavor." World War II was waged on land, on sea, and in the air over several diverse theaters of operation for approximately six years. The following essay on the wartime mobilization effort supplements a series of studies on the Army's campaigns of that war.