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.  WEI was contracted by the U.S. Army Corps of Engineers to clean and repair the original marble monument, which had last been repaired 20 years before.  While the repairs were very good, they had reached their life span and were beginning to erode and fail.  

A team of conservators and masons from WEI cleaned the marble as gently as possible, removing all biological growth and as much atmospheric soiling as feasible without harming the marble surface.  After the marble was cleaned, WEI cut out the mortar and removed the previous grout from the cracks.  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 monument was also re-pointed.  Documentation of the cracks and their progression included photogrammetry; all work was documented with photographs and measured drawings, included in a final treatment report.

The team was required to work at night while the cemetery was closed to the public and remove all evidence of our work each morning before it opened.  The visitor 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 recent controversy over its preservation or replacement has created a sensitive public relations climate for the project.  APS worked 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.