The German Secret Service in America 1914-1918 by John Price Jones

A nation at war wants nothing less than complete information of her enemy. It is hard for the mind to conceive exactly what “complete information” means, for it includes every fact which may contain the lightest indication of the enemy strength, her use of that strength, and her intention. The nation which sets out to obtain complete information of her enemy must pry into every neglected corner, fish every innocent pool, and collect a mass of matter concerning the industrial, social and military organization of the enemy which when correlated, appraises her strength—and her weakness. Nothing less than full information will satisfy the mathematical maker of war.

Germany was always precociously fond of international statistics. She wanted—the present tense is equally applicable—full information of America and her allies so as to attack their vulnerable points. She got a ghastly amount of it, and she attacked. This book sets forth how secret agents of the Teutonic governments acting under orders have attacked our national life, both before and after our declaration of war; how men and women in Germany’s employ on American soil, planned and executed bribery, sedition, arson, the destruction of property and even murder, not to mention lesser violations of American law; how they sought to subvert to the advantage of the Central Powers the aims of the Government of the United States; how, in short, they made enemies of the United States immediately the European war had broken out.