The World War I "Unknown" is a recipient of the Medal of Honor, the Victoria Cross, and several other foreign nations' highest service awards.

On March 4, 1921, the United States Congress approved the burial of an unidentified American serviceman from World War I in the plaza of the new Memorial Amphitheater.

A design competition was held and won by architect Lorimer Rich[nb 1] and sculptor Thomas Hudson Jones.

His remains were positively identified in 1998 through DNA testing as First Lieutenant Michael Blassie, United States Air Force, and were removed.

[7] On Memorial Day, 1921, four unknown servicemen were exhumed from four World War I American cemeteries in France, Aisne-Marne, Meuse-Argonne, Somme, and St. Mihiel.

Edward F. Younger, who was wounded in combat, highly decorated for valor and received the Distinguished Service Cross, selected the Unknown of World War I from four identical caskets at the city hall in Châlons-en-Champagne, France, on October 24, 1921.

On November 11, 1921, President Warren G. Harding officiated at the interment ceremonies at the Memorial Amphitheater at Arlington National Cemetery.

During the ceremony, the World War I Unknown was awarded the Victoria Cross by Admiral of the Fleet Lord Beatty, on behalf of King George V of the United Kingdom.

Other Allied nations also awarded the American Unknown Soldier with decorations, including the Legion of Honour, Médaille Militaire, and Croix de Guerre from France, the War Cross from Czechoslovakia, the Gold Medal for Bravery from Italy, the Virtuti Militari from Poland, and the Virtutea Militara from Romania.

[13] Earlier, on October 17, 1921, the British Unknown Warrior had been conferred the U.S. Medal of Honor by General of the Armies John Pershing.

The World War II Unknown was selected from remains exhumed from cemeteries in Europe, Africa, Hawaii, and the Philippines.

The caskets of the WWII and Korean unknowns arrived in Washington on May 28, 1958, where they lay in the Capitol Rotunda[11] until the morning of May 30, when they were carried on caissons to Arlington National Cemetery.

[16] The Vietnam Unknown service member was originally designated by Medal of Honor recipient U.S. Marine Corps Sgt.

The designated Vietnam Unknown was transported aboard USS Brewton, where the Marines stood guard over the casket during the voyage to Naval Air Station Alameda, California.

[11] While on display for public viewing, all branches of the U.S. Armed Forces stood in honor, guarding the casket of the Unknown for two weeks.

Sampley published an article in his newsletter and contacted Blassie's family, who attempted to pursue the case with the Air Force's casualty office without result.

In January 1998, CBS News broadcast a report based on Sampley's investigation which brought political pressure to support the identification of the remains.

The sentinels will confront people who cross the barriers at the tomb or whom they perceive to be disrespectful or excessively loud; requesting all in attendance to remain silent and standing prior to the beginning of a guard change.

On November 9–10, 2021, in honor of the Tomb of the Unknown Soldier's centennial commemoration, members of the public were allowed to walk on the plaza and lay flowers for the first time since 1925.

[26] Arlington National Cemetery has permitted the public to lay flowers at the Tomb on the three succeeding Memorial Days since the Centennial.

Once under control, the sentinel then walks on the pavement to the other side of the mat, turns to shoulder arms, and resumes the routine from the point of interruption.

While Arlington National Cemetery is open, during the day in the summer months from April 1 to September 30, the guard is changed every half hour.

[31] A civilian guard was first posted at the Tomb on November 17, 1925, to prevent, among other things, families from picnicking on the flat marble slab with views of the city.

After serving honorably for a period of nine months, and having passed the sequence of tests, a tomb guard is permanently awarded the Badge.

In 1963, a regulation was enacted that allowed the badge to be worn as a permanent part of the military uniform, even after the soldier's completion of duty at the Tomb of the Unknowns.

Officials at Arlington National Cemetery determined that proper repair could return the Tomb Monument to an acceptable appearance.

The Trust expressed concern that Arlington National Cemetery sought to replace the existing monument with marble from the original quarry, which experts agreed was likely to eventually crack.

In 2007, Mary Oehrlein informed Congressional staff members that: "The existing monument can easily be repaired, as was done 17 years ago, using conventional conservation methods to re-grout the cracks.

In June 2009 Arlington National Cemetery and the U.S. Army Corps of Engineers announced that the monument was to be repaired, not replaced.

[48] In September 2011, the cracks were filled again[47] and on October 21, 2011, inspection by the Corps of Engineers and other experts pronounced the repairs a success.