The families of Gunnery Sgt. Thomas J. Sullivan, Staff Sgt. David Wyatt, Sgt. Carson Holmquist and Lance Cpl. Squire Wells, are presented the Purple Heart honoring the Marines' sacrifice, at the Hunter Museum of American Art in Chattanooga, Tenn., April 20, 2016. The Marines were honored for giving their lives to protect others when they were attacked by a gunman at the Naval Operational Support Center and Marine Corps Reserve Center in Chattanooga on July 16, 2015.(U.S. Marine Corps photo by MSgt. John Lee, II / Released)