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 provision of muskets and cannon for the vast army of volunteers that flocked to Washington in answer to President Lincoln's call for troops, presented a problem hardly second in importance to the actual organization and training of these citizen soldiers. As the United States had but a small regular army, there were no extensive stores of arms and munitions of war, nor were there large Government manufactories or arsenals adequate to supply great armies. The opening of the Civil War found the Federal War Department confronted, therefore, with an extraordinary situation. From scientific experiment and the routine of a mere bureau, whose chief duties were the fabrication and test of the ordnance required by the small regular army, the Ordnance Department suddenly was called upon to furnish from its all too meager supply, tens of thousands of weapons for the different arms of the service, on a scale quite unprecedented in the military operations theretofore attempted in the United States.

Enjoying a reputation for scientific and painstaking work, especially in the making of large cast-iron cannon, it early became apparent that, in the event of hostilities, there must be a wide extension of the activities of the Ordnance Department. Accordingly, at the outbreak of the war the Ordnance Department was reorganized, and the new organization provided for a chief of ordnance with the rank of brigadier-general, two colonels, two lieutenant-colonels, four majors, twelve captains, twelve first lieutenants, and twelve second lieutenants.