Defense Secretary Dr. Mark T. Esper swears-in retired Navy Rear Adm. Kenneth Braithwaite to serve as the next Secretary of the Navy, in Washington, D.C., May 29. - Defense Secretary Dr. Mark T. Esper swears-in retired Navy Rear Adm. Kenneth Braithwaite to serve as the next Secretary of the Navy, in Washington, D.C., May 29.

A graphic in support of content about the Secretary of the Navy. - A graphic in support of content about the Secretary of the Navy.

Gen. Robert B. Neller, the 37th and new Commandant of the Marine Corps, speaks during his passage of command ceremony at Marine Corps Barracks Washington, D.C., Sept. 24, 2015. Gen. Dunford relinquished the position to Gen. Robert B. Neller after being confirmed to succeed U.S. Army Gen. Martin Dempsey as Chairman of the Joint Chiefs of Staff. - Gen. Robert B. Neller, the 37th and new Commandant of the Marine Corps, speaks during his passage of command ceremony at Marine Corps Barracks Washington, D.C., Sept. 24, 2015. Gen. Dunford relinquished the position to Gen. Robert B. Neller after being confirmed to succeed U.S. Army Gen. Martin Dempsey as Chairman of the Joint Chiefs of Staff.

Battle crosses are mounted on stage at the Mckenzie Arena at the University of Tennessee at Chattanooga, Aug. 15, 2015. The battle crosses are symbolic replacements for crosses for service members who have fallen in the line of duty. Four Marines and one sailor died during a shooting in Chattanooga, Tennessee, July 16, 2015. - Battle crosses are mounted on stage at the McKenzie Arena at the University of Tennessee at Chattanooga, Aug. 15, 2015. The battle crosses are symbolic replacements for crosses for service members who have fallen in the line of duty. Four Marines and one sailor died during a shooting in Chattanooga, Tennessee, July 16, 2015.