For the brave American soldiers who have lost their lives, yet somehow go unrecognized, President Warren G. Harding created a Tomb for the Unknowns on Veterans Day, 1921. The first soldier interred died in World War I. Three more unknown soldiers were eventually interred in the tomb at Virginia's Arlington National Cemetery, one from WWII, one from the Korean War and one from the Vietnam War.
In 1998, using new DNA testing, the soldier from Vietnam was identified as Michael Joseph Blassie, an Air Force pilot shot down in 1972. Blassie was moved to St. Louis to be near his family. Rather than replacing him with another unknown soldier from the Vietnam War, an inscription was added to honor the servicemen missing between 1958 and 1975.
Since 1937, the Tomb of the Unknowns, most commonly called the Tomb of the Unknown Soldier, has been guarded 24 hours a day, 365 days per year, by members of "The Old Guard" (3rd U.S. Infantry Regiment).