On March 4, 1921, the United States Congress approved the burial of an unidentified American soldier from World War I in the plaza of the Memorial Amphitheater at Arlington National Cemetery. Designed by architect Lorimer Rich and sculpted by Thomas Hudson Jones, the neoclassical white marble sarcophagus includes a relief of Peace, Victory and Valor on the east panel that faces Washington, D.C., three wreaths on each side, and an inscription on the west: “HERE RESTS IN HONORED GLORY AN AMERICAN SOLDIER KNOWN BUT TO GOD.” The Tomb sarcophagus was placed above the grave of the Unknown Soldier of World War I in 1932.
Cracks in the die block were first noted in 1963. APS was contracted by the U.S. Army Corps of Engineers to clean and repair the original marble monument, which was last repaired 20 years ago. While the repairs were very good, they had reached their life span and were beginning to erode and fail.
The marble was cleaned as gently as possible, removing all biological growth and as much atmospheric soiling as feasible without harming the marble surface. After cleaning, the existing grout was removed from the cracks, and the mortar removed to a depth of ½ inch. Conservators formulated a grout to match the marble and conceal the crack as well as possible, and filled the cracks flush with the surface of the stone; the joints were repointed with a similar strength mortar. Documentation of the cracks and their progression included photogrammetry; all work was documented with photographs and measured drawings, included in a final treatment report.WEI performed work both prior to and immediately after the 2011 earthquake, and so was able to document the immediate effect on the monument. WEI performed work at night while the cemetery was closed to the public. The visitors experience was not to be affected, and this precluded any measures to enclose the work done each night.
Communications between all parties involved, including the Old Guard soldiers who guard the tomb, meant the work progressed smoothly and quickly. Due to the powerful symbolic nature the Tomb of the Unknowns has for the country, the controversy over its preservation or replacement created a sensitive public relations climate for the project. All work was coordinated closely with Arlington National Cemetery and the Corps of Engineers to finish the work as quickly and quietly as possible and made sure all parties were informed of recent developments so that the work was either invisible or pleasing to the visitors, the preservation community, or the government. Careful documentation of the work supported the decisions made by ANC and the USACE in conserving the monument, and to provide data for future conservation.