“domestic ‘terrorists’ and ‘southern revolt’?”
Southerners might have an issue with your characterization.
And I suggest you brush up on your American history.
Local Observances Claim To Be First
“Local springtime tributes to the Civil War dead already had been held in various places. One of the first occurred in Columbus, Miss., April 25, 1866, when a group of women visited a cemetery to decorate the graves of Confederate soldiers who had fallen in battle at Shiloh...Approximately 25 places have been named in connection with the origin of Memorial Day, many of them in the South where most of the war dead were buried.”
Memorial Day Background
History of Memorial Day
UNITED STATES DEPARTMENT OF VETERANS AFFAIRS
http://www1.va.gov/opa/speceven/memday/history.asp#hist
I’m from the south. Your example is in April.
Even after Memorial Day was adopted in the south, Decoration Day (the day when Confederate Graves were cleaned and decorated) was also celebrated as a separate holiday.