Marines with 2nd Battalion, 23rd Marine Regiment conduct the Mobile Assault Course Defense at Training Area Prospect as a part of Unit Deployment Program 19.1 aboard the Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., Aug 9, 2018. The purpose of UDP 19.1 is to sharpen technical and tactical skills in the field to ensure mission success. (U.S. Marine Corps video by Pfc. Robin Lewis)
