Tomb of the Unknown Soldier

On May 30, 1958, two unidentified soldiers killed in WW II and the Korean War were buried in Arlington National Cemetery at the Tomb of the Unknown Soldier. From the article:

"The Tomb of the Unknown Soldier

The Tomb of the Unknown Soldier, with carved figures representing Peace, Victory, and Valor
The Tomb of the Unknown Soldier, Arlington National Cemetery's most iconic memorial, stands atop a hill overlooking Washington, D.C. The neoclassical, white marble sarcophagus depicts three carved Greek figures representing Peace, Victory, and Valor. Inscribed on the back of the Tomb are the words:

Here rests in honored glory an American soldier known but to God

The Tomb sarcophagus stands above the grave of the Unknown Soldier of World War I. To the west are the crypts for an Unknown Soldier from World War II and the Korean War. A white marble slab flush with the plaza marks each crypt.

The Unknown of World War I
On March 4, 1921, Congress approved the burial of an unidentified American soldier from World War I in the plaza of Arlington National Cemetery's new Memorial Amphitheater. The journey of the World War I Unknown to Arlington began in France in September 1921, when four American bodies were exhumed from unmarked battlefield graves. U.S. Army Sgt. Edward F. Younger (a World War I veteran who was wounded in combat and received the Distinguished Service Medal) selected the Unknown Soldier from among four identical caskets at city hall in Chalons-sur-Marne, France. Amid pomp and circumstance, the chosen casket was then transported to Washington, D.C. aboard the Navy cruiser USS Olympia. Those remaining in France were interred in the Meuse-Argonne American Cemetery, one of several dozen foreign cemeteries operated by the American Battle Monuments Commission.

The World War I Unknown arrived in Washington on November 9, 1921 and lay in state at the Capitol Rotunda for two days. Some 90,000 visitors lined up to pay their respects. On Armistice Day (November 11) 1921, body bearers from the Army, Navy and Marine Corps transported the casket to a caisson for the large ceremonial procession to Arlington National Cemetery. At the Memorial Amphitheater, President Warren G. Harding officiated at a ceremony attended by over 5,000 people. The U.S. Marine Corps band played the national anthem, followed by the Army Chief of Chaplains' invocation and two minutes of silence. President Harding then addressed the crowd and placed the Medal of Honor and Distinguished Service Cross on the casket. Foreign dignitaries added more medals. The ceremony then moved to the east front of the Amphitheater, where, as a battery cannon fired three salvos, the casket was lowered into the crypt. A bugler played Taps, followed by the battery firing a 21-gun salute. The Unknown Soldier was home.

In the following years, thousands of people flocked to Arlington National Cemetery to pay their respects at the Tomb of the Unknown Soldier, which soon came to symbolize the sacrifices of all American service members. While the Tomb drew many respectful mourners, it also became a tourist destination. Photographers stationed themselves by the Tomb and charged people to take their picture, and visitors left trash strewn around the site. In 1926, Congress established a military guard to protect the Tomb during daylight hours. Since midnight on July 2, 1937, the Army has maintained a 24-hour guard over the Tomb. Sentinels of the 3rd U.S. Infantry, "The Old Guard," assumed these duties on April 6, 1948, maintaining a constant vigil regardless of weather conditions.

The Unknowns of World War II and Korea
War in Korea (1950-1953) delayed plans to inter an unknown soldier from World War II at Arlington National Cemetery until 1958. President Dwight D. Eisenhower had signed a bill in August 1956 to select and pay tribute to the unknowns of World War II and Korea, but the selection process for the World War II Unknown proved more difficult than the World War I process, since Americans had fought on three continents. The Army ultimately exhumed eighteen bodies from North Africa, Europe, the Philippines and Hawaii; two Unknowns were chosen, representing the European and Pacific Theaters of the conflict. They were placed in identical caskets aboard the USS Canberra, a guided-missile cruiser off the Virginia capes. Navy Hospitalman 1st Class William R. Charette, then the Navy's only active-duty Medal of Honor recipient, selected the Unknown Soldier of World War II. The remaining casket received a solemn burial at sea.

The Korean War had its own share of unknown soldiers. North Korean forces killed and captured a number of American soldiers during their initial offensive in June 1950, and when the Chinese entered the war that fall, they overran a number of temporary cemeteries. Army officials chose one unknown casket from four exhumed from the National Memorial Cemetery of the Pacific in Hawaii.

On May 28, 1958, caskets bearing the Unknowns of World War II and Korea arrived in Washington, where they lay in state at the Capitol Rotunda until May 30, 1958. The caskets were rotated such that each unknown serviceman rested on the "Lincoln catafalque," a raised platform that had held President Lincoln's casket in April 1865. On May 30, then the official date of Memorial Day, caissons transported the Unknowns to Arlington, where they were interred in the plaza beside their World War I comrade. President Eisenhower awarded each the Medal of Honor.

The Unknown of Vietnam
The United States' involvement in the Vietnam War deeply divided the nation. Leaders anguished over how to commemorate the conflict. In 1978, President Jimmy Carter dedicated a plaque at Memorial Amphitheater which commemorated those missing in action from the Vietnam War. There were few unknown burials in Vietnam, however, due to advances in technology that facilitated the identification of remains. Nonetheless, President Ronald Reagan and much of the American public wanted to honor Vietnam veterans by interring an unknown soldier at Arlington and pushed for a selection to be made. On May 17, 1984, U.S. Marine Corps Sgt. Maj. Allan Jay Kellogg, Jr., a Medal of Honor recipient, chose an Unknown from the Vietnam War during a ceremony at Pearl Harbor, Hawaii. As with the Unknowns from previous conflicts, the casket first lay in state at the Capitol Rotunda and was transported via caisson to Arlington. On Memorial Day (May 28) 1984, President Reagan presided over the interment ceremony and presented the Vietnam Unknown with the Medal of Honor. In his eulogy, Reagan assured the audience that the government would continue looking for the war's missing in action.

For almost fourteen years, the Vietnam Unknown laid in rest at the Tomb, while Department of Defense scientists and family members of the war's few remaining unknowns worked to identify him. The remains were exhumed on May 14, 1998 to undergo mitochondrial DNA testing. Scientists identified the remains as those of Air Force 1st Lt. Michael Joseph Blassie, who had been shot down and killed near An Loc, Vietnam on May 11, 1972. According to the wishes of his family, Blassie was reinterred at Jefferson Barracks National Cemetery in St. Louis, Missouri.

The crypt designated for the Vietnam Unknown remained vacant until September 17, 1999 — National POW/MIA Recognition Day — when it was rededicated to honor all missing U.S. service members from the Vietnam War. The empty crypt is now inscribed with the words, 'Honoring and Keeping Faith with America's Missing Servicemen, 1958-1975.'"