A Neros Archer drone at the Modern Day Marine symposium in Washington, D.C. on Tuesday. Lance Cpl. Kiara Rawls/US Marine Corps Marines face a new strain as tens of thousands of drones are set to enter the force. Lithium batteries require special measures, and can catch fire if stored improperly. Marines say they need more drones that can speak a universal language. The Marine Corps is preparing to field tens of thousands more drones for troops to watch and attack enemy positions, and leader...