This invaluable resource offers students a comprehensive overview of the Manhattan Project and the decision to drop the atomic bomb, with more than 80 in-depth articles on a variety of topics and dozens of key primary source documents.This book provides everything readers need to know about the Manhattan Project, the U.S. program that led to the development of the atomic bomb during World War II. It begins with a detailed introduction to the project and includes an alphabetical collection of relevant entries on such topics as the Enola Gay, the first aircraft to drop an atomic bomb; Enrico Fermi, creator of the first nuclear reactor; Hiroshima, the target of the first atomic bomb; and Robert Oppenheimer, director of the Manhattan Project.Dozens of primary sources include eyewitness accounts, government memos, letters, press releases, and other important documents relevant to the establishment and success of the Manhattan Project. A set of four essays written by prominent scholars address whether the United States was justified in dropping the atomic bomb on Japan. The book also includes a comprehensive chronology that reveals key moments related to the creation of the world's first nuclear weapon as well as a bibliography of resources that points readers toward additional information on the Manhattan Project, nuclear weapons, and World War II.