Memorial Day was originally called Decoration Day, it was created to honor those who were killed during the War Between the States (U.S. Civil War) and from 1868 to 1970 it was observed on the 30th of May.
Silent film from 30MAY1946; General George S. Patton is honored with a posthumously awarded medal, as well as Allied officials honoring all the fallen U.S. military personnel buried in the American Cemetery in Hamm, Luxembourg:
Because many U.S. states, and cities, preferred to say ‘Memorial Day’, in 1967 the U.S. Congress officially changed the name of Decoration Day to Memorial Day.
In 1968, the observance of Memorial Day was changed to the last Monday in the month of May, an intentional move by the U.S. Congress to create a three day weekend holiday, however, the date change did not go into effect until 1971.
2018 U.S. Department of Defense video explaining the difference between Memorial Day and Veterans Day:
Memorial Day: The First 101 years (1868 – 1968)
Biden’s War, 2022: RHODE ISLAND MILITIA DEPLOYS ON MEMORIAL DAY!