(WASHINGTON) — President Joe Biden was headed to Arlington National Cemetery on Memorial Day to take part in the traditional wreath-laying at the Tomb of the Unknown Soldier, along with first lady Jill Biden and Vice President Kamala Harris.

He was then set to speak at the Arlington’s amphitheater as the nation observes the 154th Memorial Day.

Defense Secretary Lloyd Austin and Joint Chiefs Chairman Mark Milley were scheduled to speak as well.

Monday’s observance comes after the Bidens spent an emotional day Sunday mourning the victims of the school shooting in Uvalde, Texas.

After arriving from Delaware Monday morning, Biden and the first lady held what has become another Memorial Day tradition: a White House breakfast for Gold Star families.

When they return to the White House from Arlington, the Bidens will be joined by families of the fallen in a tree-planting ceremony on the White House South Lawn.

They’ll plant a magnolia tree in honor of those who lost their lives in service to the nation.

Memorial Day was originally know as Decoration Day, designated in 1868 after the Civil War to decorate the graves of soldiers.

It became a federal holiday in 1971.

According to the cemetery’s website, members of the 3rd U.S. Infantry Regiment — known as “The Old Guard” — decorate the graves with small American flags on the Thursday before Memorial Day, known as the “Flags in” ceremony.

In the space of a few hours, Old Guard service members plant flags in front of approximately 280,000 headstones and the bottom of about 7,000 niche (for cremated remains) rows — a tradition since 1948.

The Tomb of the Unknown Soldier was dedicated in 1921 after four unknown Americans were exhumed from cemeteries in France following World War I.

The remains of Americans killed in World War II, the Korean War and the Vietnam war were added in the years after.

Soldiers from the regiment — known as Sentinels — keep solemn watch at the Tomb all day and night, 365 days a year, in any weather.

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