HMS Sword is a fictional experimental submarine of the British Royal Navy in Jules Verne's 1896 novel Facing the Flag. As described by Verne, Sword was a "submersible boat of only twelve tons", carrying a crew of four and commanded by a lieutenant. Her screw was worked by a couple of dynamos fitted with accumulators that needed to be charged in port, and which enabled her to cruise for only one or two days. She was divided into three watertight compartments. The aft one contained the accumulators and machinery. The middle, occupied by the pilot, was surmounted by a periscope fitted with lenticular portholes through which an electric search-lamp lighted the way through the water. The forward compartment was used for passengers.