U.S. Air Force Lt. Gen. Richard Clark, 3rd Air Force commander, salutes a remembrance wreath on behalf of United States Air Forces in Europe during the Memorial Day Ceremony at Luxembourg American Military Cemetery in Hamm, Luxembourg, May 26, 2018. Memorial Day is observed on the last Monday of May in remembrance of those who gave the ultimate sacrifice and is said to have originated after the American Civil War. (U.S. Air Force photo by Senior Airman Dawn M. Weber)