HMS M1

HMS M1 was a unique Royal Navy submarine monitor of the First World War. She was the lead ship of her class, designed to carry a massive 12-inch naval gun for engaging coastal targets. Her service was brief, and she was lost with all hands in a tragic collision in 1925, leaving a historically significant wreck on the seabed.

Design and description

The M-class submarines were conceived as a radical solution for coastal bombardment, a role traditionally filled by surface ships like monitors. The design was developed under the direction of the Admiralty's Director of Naval Construction, Eustace Tennyson d'Eyncourt. The most extraordinary feature was the installation of a single BL 12-inch Mk IX gun removed from the *Majestic*-class battleship HMS *Mars*. This weapon, housed in a watertight turret forward of the conning tower, could only be loaded and fired on the surface. The submarine's hull was based on that of the earlier K-class, but was heavily modified to accommodate the gun's weight and recoil. Other armament included four torpedo tubes. Propulsion was provided by diesel engines for surface running and electric motors for submerged operation, a standard configuration for the era.

Construction and career

HMS M1 was ordered under the Emergency War Programme of 1916 and her keel was laid down at Vickers shipyard in Barrow-in-Furness. She was commissioned in April 1918, late in the First World War. Following the Armistice of 11 November 1918, she was assigned to the Atlantic Fleet for trials and training exercises. During the early 1920s, she operated with the Home Fleet, participating in fleet manoeuvres and testing the novel concept of the submarine monitor. Her sisters, M2 and M3, were later converted for other experimental roles, but M1 retained her original gun armament throughout her service.

Loss

On 12 November 1925, M1 was engaged in a routine exercise in the English Channel. While submerged off Start Point, Devon, she was accidentally rammed by the Swedish merchant vessel SS Vidar. The collision was catastrophic, tearing a large hole in the submarine's pressure hull forward of the conning tower. M1 sank almost immediately in approximately 70 metres of water, taking her entire crew of 69 men to their deaths. A subsequent Board of enquiry investigated the disaster, which occurred in busy shipping lanes under conditions of poor visibility. The loss highlighted the peacetime dangers of operating large submarines in congested waters and led to increased scrutiny of procedures.

Wreck

The wreck of M1 was located in 1967 by a diving team led by John Grattan. It rests upright on a silty bottom, with the massive 12-inch gun still clearly visible in its turret. The site is designated as a Protected Wreck under the Protection of Wrecks Act 1973, administered by Historic England. The wreck is considered a war grave, and diving is restricted to licensed archaeological investigation. Surveys have shown the hull to be largely intact, though the damage from the collision with SS Vidar is evident. The site provides a unique archaeological snapshot of an experimental and short-lived warship design from the early 20th century. Category:Royal Navy submarines Category:Shipwrecks in the English Channel Category:Maritime incidents in 1925