Waterport Casemates were part of the City Defence between Western Places of Arms and Montague Bastion. This outer defence wall protected the main gates to the Grand Casemates. Provided direct fire into the harbour area and along the Old Mole.
In 1856 returns shows that there were sixteen 32-pdr mounted on the ramparts of Waterport Casemates.
By 1888 some ten guns are shown as emplaced here,
- Eight 64/32 lbs RML (rear chock)
- Two 32lbs SB 42-cwt (garrison standing)