Source: https://www.military.com/holidays/memorial-day/how-decoration-day-becam…

Memorial Day was not always known by that name, and it was not always celebrated on the last Monday in May. It was originally called Decoration Day and was celebrated on May 30. This is the history of this patriotic day.

The years following the end of the Civil War in 1865 saw American communities tending to the remains and graves of an unprecedented number of war dead. All of the previous wars and conflicts fought by the United States combined would still not add up to the body count produced by the Civil War.

On the first official Decoration Day – May 30, 1868 – Ohio Representative James A. Garfield, a former general and future U.S. president, addressed a crowd of 5,000 gathered at Arlington National Cemetery:

“Hither our children’s children shall come to pay their tribute of grateful homage. For this are we met today. By the happy suggestion of a great society, assemblies like this are gathering at this hour in every State in the Union.

Thousands of soldiers are today turning aside in the march of life to visit the silent encampments of dead comrades who once fought by their side.

From many thousand homes, whose light was put out when a soldier fell, there go forth today to join these solemn processions loving kindred and friends, from whose heart the shadow of grief will never be lifted till the light of the eternal world dawns upon them.”

After Garfield spoke, the 5,000 visitors made their way into the cemetery to visit the tens of thousands of graves in the newly formed Arlington National Cemetery.

But Decoration Day was not an official holiday. May 30 was a day touted by the Grand Army of the Republic, an association of Union Civil War veterans, as an official day of remembrance for people across the country. The idea was to honor the war’s dead by decorating the graves of Union soldiers.