A Marine with 1st Law Enforcement Battalion, I Marine Expeditionary Force Headquarters Group, I MEF practices his community engagement with a role-player during mobile immersion training at Marine Corps Base Camp Pendleton, Calif., Nov. 20, 2015. Mobile immersion training is a scenario-based training exercise in which the Marines engage in locating, apprehending and transporting a high-value individual. - A Marine with 1st Law Enforcement Battalion, I Marine Expeditionary Force Headquarters Group, I MEF practices his community engagement with a role-player during mobile immersion training at Marine Corps Base Camp Pendleton, Calif., Nov. 20, 2015. Mobile immersion training is a scenario-based training exercise in which the Marines engage in locating, apprehending and transporting a high-value individual.