In earlier biographies by Winfried Lüdecke and Pepita Bobadilla, Reilly is described as living as a spy in Wilhelmine Germany from 1917 to 1918. Drawing upon the latter sources, Richard Deacon likewise asserted that Reilly had operated behind German lines on a number of occasions and once spent weeks inside the German Empire gathering information about the next planned thrust against the Allies. However, most later biographies concur that Reilly's activities in the United States between 1915 and 1918 precluded any such escapades on the European Front. Later biographers believe that Reilly, while lucratively engaged in the munitions business in New York City, was covertly employed in British intelligence in which role he may well have participated in several acts of so-called "German sabotage" deliberately calculated to provoke the United States to enter the war against the Central Powers.