Every Memorial Day, a wreath laying ceremony is held at the Tomb of the Unknown Soldier in Arlington National Cemetery. Most of us know that the white marble sarcophagus represents all the unknown soldiers who died serving the nation, but what about the three marble slabs below it?

Here are the stories of each grave.

The Unknown of World War I

When World War I ended in 1918, the American Expeditionary Forces (AEF) deployed throughout Europe had lost more than 160,000 troops, and less than 2,000 of them remained unidentified. Most of the identified remains were returned home, while around 31,000 stayed in newly established cemeteries in Europe. As for the unidentified remains, some suggested to make a memorial to an unknown soldier to represent all of the unidentified fallen. However, these proposals were rejected by Army leaders.

Armistice Day, 1920, changed their minds. Great Britain and France each held elaborate funerals to bury an unknown soldier at the Westminster Abbey and the Arc de Triomphe. This swayed the public opinion across the Atlantic, and President Woodrow Wilson signed the legislation to honor an unknown soldier at Arlington on March 4, 1921.

A few months later, four unknowns were exhumed on Memorial Day from four different World War I American cemeteries in France. On October 24, 1921, at the city hall in Chalons-sur-Marne, France, U.S. Army Sgt. Edward F. Younger, recipient of the Distinguished Service Medal in “The Great War, the war to end all wars”, chose the first Unknown among four identical caskets. He selected the third casket from the left by placing a spray of white roses on it, and the casket was transported to the U.S. aboard the USS Olympia. On November 11, 1921, the Unknown of World War I was interred at the Memorial Amphitheater at Arlington National Cemetery. The other three were buried in the Meuse Argonne Cemetery in France.

The Unknown of World War II and Korea

Following the end of World War II, the U.S. Congress and President Harry Truman legislated the internment of a World War II unknown. But these plans had to be postponed when the Korean War broke out on June 25, 1950. Three years after the Korean War ended, President Dwight Eisenhower signed a new law for the double interment of a World War II and a Korean War unknown.

The Army chose two finalists for the World War II unknown, one from the Atlantic Theater and the other form the Pacific Theater. Meanwhile, four unknowns of the Korean War were exhumed from the National Cemetery of the Pacific in Hawaii, and Army Master Sgt. Ned Lyle chose the Unknown of Korea among them. The Unknown of Korea and the two unknowns of World War II were taken aboard the USS Canberra, where Navy Hospitalman 1st Class William R. Charette, the Navy’s only active-duty Medal of Honor recipient at the time, selected the Unknown Soldier of World War II. The other World War II unknown had a solemn burial at sea.

The Unknown of World War II and Korea arrived in Washington on May 28, 1958 and laid in the Capitol Rotunda until Memorial Day. On May 30th, they had a grand procession to Arlington National Cemetery, where President Eisenhower awarded the Medal of Honor to each of the unknowns, before they were interred beside the Unknown of World War I.

The Unknown of Vietnam

As the Unknown of World War II and North Korea arrived in Arlington, American troops have started arriving in Vietnam. Over the years, Air Force First Lieutenant Michael Joseph Blassie came to join the Vietnam troops, but his aircraft was shot down on May 11, 1972. Upon their recovery five months later, his remains were tentatively identified, but were reclassified as unidentified sometime afterwards.

In 1973, Congress directed the burial of an Unknown of Vietnam at Arlington following the Paris Peace Accords. In 1974, a crypt for the new unknown was built between the other two, although it remained empty for several years.

During a ceremony at Pearl Harbor on May 17, 1984, U.S. Marine Corps Sgt, Maj. Allan Jay Kellog Jr., a Medal of Honor recipient, designated the Unknown of Vietnam. The remains he selected were formerly identified as those of First Lieutenant Blassie, filling the empty crypt on May 28, 1984.

When his family learned that First Lieutenant Blassie might have been buried as the Unknown of Vietnam, they petitioned the Department of Defense to open the site and conduct a DNA test on the remains. On May 14, 1998, the remains were exhumed and were eventually identified as those of First Lieutenant Blassie, based on mitochondrial DNA testing. His remains were buried with full military honors in Jefferson National Cemetery, Missouri on July 11, 1998.

To this day, the crypt of the Unknown of Vietnam remains vacant. However, the cover was replaced with one that bears the inscription “Honoring and Keeping Faith with America’s Missing Servicemen, 1958-1975”.

We may celebrate Memorial Day in many ways. Some might prefer to bask under the Florida sun in Key West, relax in a hotel room in Door County, or go exploring a foreign country. But every once in a while, we could pay our respects to the unidentified fallen soldiers represented by the Tomb of the Unknown Soldier and its three graves.