A vital instrument of power, telecommunications is and has always been a political technology. In this book, Headrick examines the political history of telecommunications from the mid-nineteenth century to the end of World War II. He argues that this technology gave society new options. In times of peace, the telegraph and radio were, as many predicted, instruments of peace; in times of tension, they became instruments of politics, tools for rival interests, and weapons of war. Writing in a lively, accessible style, Headrick illuminates the political aspects of information technology, showing how in both World Wars, the use of radio led to a shadowy war of disinformation, cryptography, and communications intelligence, with decisive consequences.