HMS M1

About

HMS M1 was a submarine of the British Royal Navy, one of four vessels of her class ordered towards the end of the First World War. She sank with the loss of her entire crew in 1925. The vessels were originally intended as "submarine monitors", but their purpose had been changed before detailed design began. M1 was fitted with a 12-inch (305mm) gun which was intended for use against surface ships in preference to torpedoes, the argument being that, "No case is known of a ship-of-war being torpedoed when under way at a range outside of 1,000 yd (914 m; 3,000 ft)."

Although the gun had an effective range of 15,000 yards (13.7 km; 8.52 mi), it was normally fired using a simple bead sight at periscope depth with only the barrel above the water. It was important for the submarine's gun to sink or disable the target with the first shot, because the gun could only be loaded on the surface. She was 295 feet 9 inches (90.14 m) long, displaced 1,950 long tons (1,980 t) submerged and operated out of Portsmouth. She was launched on 9 July 1917, but was not involved in active service in the First World War. In 1923, water leaking into the barrel of the gun resulted in extensive damage to the muzzle...