Marines with 2nd Combat Engineer Battalion set up an explosive charge on a rooftop during their urban breaching training exercise on Engineer Training Area-1 aboard Marine Corps Base Camp Lejeune, N.C., Feb. 19, 2015. During the training, the unit learned how to open any type of door, gate or roof using a variety of tools, from explosives to shotguns and sledge hammers. They learned to do whatever was necessary to allow the infantry squad they were supporting to enter the building. - Marines with 2nd Combat Engineer Battalion set up an explosive charge on a rooftop during their urban breaching training exercise on Engineer Training Area-1 aboard Marine Corps Base Camp Lejeune, N.C., Feb. 19, 2015. During the training, the unit learned how to open any type of door, gate or roof using a variety of tools, from explosives to shotguns and sledge hammers. They learned to do whatever was necessary to allow the infantry squad they were supporting to enter the building.