Official Records of the Union and Confederate Armies
The Official Records of the Union and Confederate Armies in the War of the Rebellion, commonly known as the Official Records of the Union and Confederate Armies or Official Records (OR or ORs), is the most extensive collection of American Civil War land warfare records available to the general public. It includes selected first-hand accounts, orders, reports, maps, diagrams, and correspondence drawn from official records of both Union and Confederate armies. History. Collection of the records began in 1864; no special attention was paid to Confederate records until just after the  capture of Richmond, Virginia, in 1865, when with the help of Confederate Gen. Samuel Cooper, Union Army Chief of Staff Maj. Gen. Henry W. Halleck began the task of collecting and preserving such archives of the Confederacy as had survived the war. In 1866 a joint resolution of Congress authorized the compilation and publication under auspices of the War Department. Eventually, seventeen Secretaries of War were involved in the process. In 1877, Army Captain Robert N. Scott was appointed by the Secretary of War as director of the Publications Office, War Records. (Scott's name appears in each volume as  the preparer, listed with the rank of brevet lieutenant colonel, 3rd U.S. Artillery.) Structure and content. The original title for the records was "The Official Records of the War of the Rebellion" and they were later renamed "The War of the Rebellion: a Compilation of the Official Records of the Union and Confederate Armies", which has led to some lasting controversy over the official name for the war. As finally published, the records consist of 138,579 pages with 1,006 maps and diagrams assembled in 128 books, organized as 70 volumes grouped in four series, published between 1881 and 1901. Each  of the four series of books in the compilation is divided into "volumes" numbered from the beginning of the series with Roman numerals. In series II, III, and IV each "volume" coincides with a book. In series I, however, it was found to be usually impracticable, beginning with volume X, to confine "volumes," as units of content, within single books. Volume X and most subsequent volumes in series I were therefore issued in "parts" distinguished by subsidiary Roman numerals, each occupying a separate book. Beginning with volume XXIV, Arabic "serial numbers" were also printed on the backs of the books  issued, although these numbers were not included on the title pages, and are therefore not universally used in citations. A final comprehensive index (Serial No. 130) was published in 1901 with remaining additions and corrections. A companion volume, the "Atlas to Accompany the Official Records of the Union and Confederate Armies", was published in 1895. It included maps of military operations (175 plates), a topographic map of the area of operations (26 plates), and some drawings of weapons, uniforms, insignia, and flags. In 1966, the U.S. National Archives began publication of a five-volume set that comprised an arguably superior  index to the Army ORs, "Military Operations of the Civil War: A Guide Index to the Official Records of the Union and Confederate Armies, 1861-1865", microfilm publication M1026. Introductory material to the guide-index offers guidance to readers of the ORs: Because of the enormous volume of material, the lengthy time period of collection and publication, and the constant and continuing process of correction by veterans of both sides still living contemporaneously, the records are perhaps the most intensely peer-reviewed documents in historical publication. Historians have argued that some of the modifications made years after the events have  decreased the accuracy of the records and were made simply to enhance personal reputations (or to denigrate the reputations of rivals). An additional 100 volumes of previously unpublished reports and correspondence were published by the Broadfoot Publishing Company of Wilmington, North Carolina, from 1995 to 1999, entitled "Supplement to the Official Records Of the Union and Confederate Armies". Further reading. While the Official Records are probably the most-used of all primary sources for historical research on the Civil War, there are other contemporary published works that provide well-sourced insights not constrained by the types of sources compiled by  government: