Memorial Day's roots can be informally traced back to May 1868, first known as Decoration Day. The holiday was meant to be a time for Americans to consider the sacrifice of those who died in the Civil War, also as a day of remembrance and national unity. Bear in mind, then-president Lincoln was assassinated just a few years earlier in 1865. Understandably, the late 1860s was a time when national unity was sorely needed.