Master Sgt. Keith Martinez, U.S. Marine Drum & Bugle Corps assistant drum major, takes the oath of enlistment during his promotion ceremony at Marine Barracks Washington, D.C., Aug. 1. - Master Sgt. Keith Martinez, U.S. Marine Drum & Bugle Corps assistant drum major, takes the oath of enlistment during his promotion ceremony at Marine Barracks Washington, D.C., Aug. 1.