In undertaking the preparation of the following chapters, which were ﬁrst published in Harper's Magazine and in Harper's Weekly, it was not expected that serious difﬁculty would be met with to obtain the data. Nevertheless, the articles were written only at the cost of the most unforeseen effort and nearly three years' time. Hundreds of letters were written to persons in almost every State in the Union, and in the Philippine Islands, Canada, France, England, Gibraltar. Frequent trips became necessary to Washington and Richmond, also to Chicago, Boston, Pittsburgh, etc. A bibliography of the books, newspapers, and pamphlets consulted would show a list of hundreds of volumes. No expenditure of time, effort, or money has been spared, not only in collecting all the data obtainable for each of the subjects, but also in verifying it—where not absolutely impossible—to the smallest detail. The following chapters are in every sense historical.
The original plan for obtaining data was to secure permission to examine the original records in the War Department, of the Bureau of National Police and the Secret Service. To this request President Wm. H. Taft, who was then Secretary of War, replied, through the Adjutant-General of the Army, that “all such documents that are of any historical interest or value, and which are in the possession of the War Department, have been published in the Ofﬁcial Records of the Union and Confederate Armies.” But though the Ofﬁcial Records approximate 139,000 pages, very little is to be found regarding the work of individual members of the Secret Service. The very nature of the work made the