Graves are decorated with flags for at Arlington National Cemetery in Arlington, Virginia, on May 26, 2008. | Wikimedia Commons/Remember Memorial Day is an annual federal observance that honors those in the U.S. military who have passed away and a day for Americans to spend time praying for "permanent peace." The holiday was observed in the 19th century under the name “Decoration Day," which sought to honor the memory of soldiers who died in the American Civil War. Later on, the observance was broadened to include Americans killed in all armed conflicts, with parades, barbeques and other festivities being connected to the holiday.