The Tomb of the American this, for a serviceman killed in WWI, was established in 1921
[DOC] [TLE] Tomb of the Unknown Soldier - Arlington National Cemetery [PAR] On Memorial Day, 1921, four unknowns were exhumed from four World War I ... 
Four unknown Americans who died in the Korean War were disinterred from the... [DOC] [TLE] Tomb of the Unknowns - Wikipedia [PAR] The Tomb of the Unknowns is a monument dedicated to American service 
members who have died without their remains being identified.