The War Department Library was designed by Richard von Ezdorf and completed in 1887. This space was occupied by the War Department until 1938 when they vacated the building. The room has a basic French Renaissance and eclectic mix of the Classical and Gothic Revival styles. The Gothic Revival was very popular in the late 19th century, and some believed it to be the "epitome of high Victorian ideals and high Victorian style."

Completed about ten years after the State Department Library, the difference in the treatment of the ironwork and the pattern of the English Minton tile floor is evident, as well as the difference in scale. The cove ceiling contains terra cotta oak leaves, and was once lit by gas jets, the pipes of which are still in place. The room is surrounded by three tiers of decorative iron-work and exposed book shelves, with quatrefoil openwork railings and columns topped with oak-leafed capitals. The ornament reflects military heraldry - the oak leaves and acorns in the ceiling and columns represent steadfastness and civic virtue, and the salamanders in the lower level shelving panels suggest bravery and courage.

The iron work in the room was constructed by the Snead Iron Works of Louisville, Kentucky. This company also constructed stairs for the Washington Monument and the cast iron stacks for the Library of Congress. The metal in the room were treated to imitate other metals. Electroplating, a fairly new process, was used, as well as two other processes - Bower-Barff and Galvano-plastic.

Restoration of this room was completed in 1985. Restoration work included paint and metals analyses. Painting was done by General Services Administration in-house painters including the touch-up of bronze powder paint. A 1995 in-depth metals analyses allows for future preservation and restoration of the metals.

Before restoration the room was used for storage and meetings, and sometime during the 1970s a drop ceiling and long curtains were installed. Today the library functions as the Executive Office of the President Law Library.