Invented in the 1830's, the telegraph soon became indispensable. By 1851 there were more than 50 companies providing telegraphic service in the United States alone. The telegraph played a pivotal role in warfare beginning with the American Civil War, featured prominently in the creation of the first large American corporation, Western Union, and made possible long distance communication with the laying of the transatlantic cable. This book describes the global impact of the telegraph from its advent to its eventual eclipse by the telephone four decades later.