Major Fischer examines the development of military night aviation from its origins through the First World War. Emphasis is on the evolution of night flying in those countries that fought on the Western Front, namely France, Germany, Great Britain, and the United States. While night flying occurred in other theaters, the most intense air effort was clearly in the west. There, belligerents pressed aviation technology and tactics to the limits. To illustrate the rapid development of night military aviation during the First World War, the author surveys the state of night flying prior to August 1914. The author concludes that the Western Front belligerents failed to appreciate and conserve the lessons of night flying learned during the First World War.