As far as possible, this work has been based on primary sources. Unlike most of his contemporaries, Ambrose Burnside did not prepare a face for the faces he would meet, and his surviving correspondence is much more limited than, for instance, that of George McClellan. What few private letters he left, save a handful in the McClellan Papers, are contained in the Burnside Papers of the National Archives, which also holds the bulk of his official paperwork; the Rhode Island Historical Society preserves a somewhat smaller collection of Burnside material, most of it related to military or business affairs. These two sets of papers remain virtually untouched by historians. The greatest single source for personal information on Burnside is the Daniel Reed Larned Papers, in the Library of Congress; Larned was close to the general from December of 1861 until the siege of Petersburg, and his letters and journal vibrate with his evaluations of Burnside the man. The relative shortage of personal papers enforced a reliance upon other period manuscripts, newspapers, edited diaries and memoirs--often disagreeably tainted by time and motive--and, as a last resort, regimental histories. Secondary histories, unless pertaining to collateral or incidental topics, are generally cited only for comparison or criticism.
Of all the debts I have accumulated in four years of work on Burnside, none exceeds the one I owe A. Wilson Greene, of the Fredericksburg and Spotsylvania National Military Park. Not only did he offer living proof of another soul who doubted the traditional estimate of Burnside, he read and carefully criticized about a third of the manuscript, vastly improving at least that third. He and his colleague at Fredericksburg, Chief Historian Robert K. Krick, allowed me the run of their holdings and untangled some confusing technical matters for me. Bob's encyclopedic knowledge of things Confederate also yielded sources I might otherwise have missed.
Thanks to Michael Pilgrim, and particularly to Michael Musick, my trips to the National Archives were much more worthwhile than they otherwise would have been; their patience and persistence in my behalf transformed a labyrinthine quest into a few productive visits. Fred Baumann similarly aided me at the Library of Congress. Suzanne Christoff, curator of the U.S. Military Academy Archives, guided me through her own department and the West Point