Complex sentence: During all of this time he remained active in the military affairs of the colony, and in 1667 he and two others were required with all possible speed to mount the great guns upon such carriages to allow for their easy conveyance from place to place.
Split into simpler sentences: During all of this time he remained active in the military affairs of the colony. That same year, he and two others were required with all possible speed to mount the great guns upon such carriages to allow for their easy conveyance from place to place.