The Washington Times has the story of
General Orders No. 11
We must cherish tenderly the memory of our heroic dead
Memorial Day has many roots. There are numerous competing claims for the first “Decoration Day,” as the holiday was known in the years after the Civil War. But the first large-scale observance took place on May 30, 1868, at the behest of Illinois congressman and former Union Maj. Gen. John A. Logan.
Gen. Logan – known affectionately as “Black Jack” – was a Mexican War veteran and a politician who commanded in the western theater and was famed for his role at the 1863 Battle of Vicksburg and other engagements. After the war, Logan was commander in chief of the Grand Army of the Republic, a Union veterans organization. On May 5, 1868, he issued General Orders No. 11, establishing May 30 as a day of remembrance for fallen comrades
Go read General Orders No. 11 at their post.