According to professor David Blight of Yale University’s History Department, the very first Memorial Day was observed by former black slaves at the Washington Race Course in Charleston, S.C., at the end of the Civil War.
The race course had been used as a temporary Confederate prison camp in 1865 as well as a mass grave for Union soldiers who died there. Immediately after the cessation of hostilities, the former slaves exhumed the bodies from the mass grave and reinterred them properly with individual graves.
They built a fence around the graveyard with an entry arch and declared it a Union graveyard. The work was completed in only 10 days.
On May 1, 1865, a crowd estimated at 10,000, including many black residents and 2,800 children, proceeded to the location for sermons, singing, and a picnic on the grounds. It was proclaimed the first Decoration Day (and later Memorial Day).
Posted by Jill on Monday, May 31, 2010
According to this site, anyway: