Player Embed Code: Download Embed Share National Memorial Day Observance Defense.gov May 28, 2018 | 48:31 President Donald J. Trump, Defense Secretary James N. Mattis, and Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, speak at the 150th Memorial Day wreath-laying ceremony at the Tomb of the Unknown Soldier, May 28, 2018, at Arlington National Cemetery, in observance of America’s fallen military service members.