The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 5: Forts and Artillery.
Francis Trevelyan Miller, Ed.

The importance of these defenses was mainly in enabling Thomas to concentrate his army at a depot well stored with munitions of war, and to hold his opponent, who was flushed with his successful march from Atlanta, in check, until the Union army was fully prepared. It is conceded by all critics that the labors of the engineer troops on these works were abundantly well spent. During the same eventful period, the fortifications constructed by them at Murfreesboro were successfully held and defended by a portion of Thomas' army.

No mention has been made of the immensely valuable services of all the engineer officers in the conduct of sieges throughout the war. No small portion of the conflict consisted in the besieging of important fortified places, and the manner in which these duties were discharged elicited high praise from all the commanding generals who had to do with such operations. Henry, Donelson, Vicksburg, Fort Fisher, the defenses of Charleston, Mobile, Savannah, and other places were all notable for the work of the besiegers, whose engineers directed and superintended the construction of the works of approach.

Justice to posterity demands that an accurate record of all the important military events of the war be preserved. No small part of that record had to be shown by maps. The chief engineer of the army directed the engraving, lithographing, photographing, and issuing of these maps, of which about twenty-four thousand five hundred sheets were sent out during the Civil War. The carefulness of the compilation often has been demonstrated. The hostile operations came to an end with the surrender of the last Confederate armed forces, but, for the construction of a basis on which accurate history might later be built, the Engineer Corps of the army continued its invaluable labors in making record of these events, which could be best depicted in map-form and in official reports. We have not even yet fully realized the immense worth of these documents of the great struggles during the Civil War.