Simcoe Guns 01: Commonwealth Culverin Drake (c. 1650)
The plaque on the wall indicates that this gun was forged in 1650 and bears the inscription of both CRII (Carolus Rex II, i.e. Charles II) and Oliver Cromwell's Commonwealth. It would have been obsolete by the time Simcoe brought it to the fort in 1793. According to the plaque, equipment shortages often caused the British to employ obsoleted equipment in colonial defence.
This gun is also apparently one of the rarest pieces of early modern British artillery.