 Complete the following phrase:  Frederick understood that the greatest threat to massed infantry was concentrated artillery fire. He realized that even small and relatively light guns could severely disrupt or destroy infantry units if they could be brought in close enough and fire often enough. But since even light foot artillery travelled at the speed of a marching soldier, the solution was to make every artilleryman a part-time horseman. Through relentless drill and discipline Frederick emphasized mobility and speed in all phases of their operations. The unit consisted of a battery of six 6-pound cannons with 48 men, including 3 officers. The battery was wiped out and reformed twice in that same year at the 