HMS M1 (M-class)

Diesel-Electric Coastal Attack Submarine [ 1918 ]

HMS M1 led her class of three-strong and featured the largest guns ever fitted to a submarine.

Authored By: Staff Writer | Last Edited: 01/06/2021 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

VIEW SPECIFICATIONS [+]

By the time of World War 1 (1914-1918), British diesel-electric submarines carried the requisite torpedo armament for undersea work and small-caliber deck guns for surface work. The latter was primarily used against poorly-defended merchant types and proved much more cost-effective when compared to a single torpedo. The same weapon could, to some extent, be brought to bear against land-based coastal targets if need be which made them a dual-purpose threat. British submarine engineers did not stop there when envisioning all-new attack weapons for their fleet of submarines and drew up plans for a submersible class of boats to be used to attack fortified shoreline defenses with full-fledged naval artillery weapons.

This resulted in the "M-class", a Royal Navy submarine group given the largest artillery weapons ever to be fitted to an undersea boat. The group comprised just three vessels in all, designated HMS M1, HMS M2, and HMS M3 and all three carried primary armament of 1 x 12" (305mm) /40 caliber Mark IX naval guns to go along with the more traditional installations of 1 x 3" (76mm) Mk II HA Anti-Aircraft (AA) gun and 4 x 18" (450mm) torpedoes. The main gun was given 50 projectiles from which to work with while only a single salvo of four torpedoes was carried - showcasing the true battlefield nature of these boats (coastal attack).

HMS M1 measured 295.8 feet and had a beam of 24.7 feet, displacing 1,620 tons when surfaced and nearly 2,000 tons when submerged. Power was from a conventional diesel-electric configuration involving 2 x Vickers 12-cylinder diesel units of 2,400 horsepower for surface propulsion and 4 x Electric motors offering 3,200 horsepower for undersea travel. These were used to drive a pair of 3-bladed shafts featured astern.

Speeds reached up to 15 knots when surfaced and fell to 9 knots when submerged. Range was 2,000 nautical miles (2,300 miles) when running on the surface at 15 knots. This could be increased to 4,500 nm (5,200 miles) when cruising at 10 knots. The hull was tested down to a depth of 200 feet.

Aboard was a typical crew complement of sixty two officers and sailors.

While given a traditional submarine-like appearance, with its tapered bow and stern to go with its sail/conning tower, the boat was immediately identifiable thanks to the massive artillery piece integrated into the hull/sail. The elevation span of the gun allowed the submarine to remain submerged while the barrel's muzzle protruded beyond the waterline. Sighting was through a periscope-and-foresight alignment which gave reasonably good accuracy as submerged, bouncing artillery pieces went. The gun fired a massive 850lb projectile towards the target/target area and its reliability was unquestioned.

As an attack submarine, the M1 was never intended to directly assail enemy submarines or even warships but instead target and destroy German emplacements and targets-of-opportunity along the conquered Belgian coastline.

One of the primary deficiencies in the concept was the requirement that the vessel be surfaced to reload. The reloading process was about as fast as reloading a land-based artillery piece - relatively quick - but the action as a whole was time-consuming and left the boat quite vulnerable to return-fire or air attack.

While three total boats were built to the M-class standard, just HMS M1 was launched and operated during the war years. She left her shipyard on July 9th, 1917 and began operations in 1918, spending some time in the Mediterranean Theater - but the war was soon over with the Armistice of November 1918 and thus she never fired her gun in anger.

In 1923, her barrel suffered firing damage from leaking water. Her end came in English Channel waters when on November 12th, 1925 when the Swedish ship SS Vidar collided with the submerged form of HMS M1. She was lost with all hands aboard. Her wreck was not discovered until 1999 at a depth of 240 feet.©MilitaryFactory.com

Note: The above text is EXCLUSIVE to the site www.MilitaryFactory.com. It is the product of many hours of research and work made possible with the help of contributors, veterans, insiders, and topic specialists. If you happen upon this text anywhere else on the internet or in print, please let us know at MilitaryFactory AT gmail DOT com so that we may take appropriate action against the offender / offending site and continue to protect this original work.

Specifications

United Kingdom
Operators

1918
Commissioned

United Kingdom
National Origin

Lost-in-Action
Project Status

62
Complement

M-class
Hull Class

4
Number-in-Class

HMS M1; HMS M2; HMS M3; M4 (not completed)
Ships-in-Class

Submerged Attack
Traveling under the surface to search, track, and / or engage or reconnoiter areas.

Maritime Patrol
Active patroling of vital waterways and maritime areas; can also serve as local deterrence against airborne and seaborne threats.

Fleet Support
Serving in support (either firepower or material) of the main surface fleet in Blue Water environments.

295.8 feet
(90.16 meters)
Length

24.7 feet
(7.53 meters)
Beam

1,620
tons
Displacement

2,000
tons
Displacement (Submerged)

2 x Vickers 12-cylinder diesel engines developing 2,400 horsepower with 4 x Electric motors generating 3,200 horsepower to 2 x Shafts astern.
Propulsion

15.0 knots
(17.3 mph)
Surface Speed

9.0 knots
(10.4 mph)
Submerged Speed

1,999 nm
(2,300 miles | 3,701 km)
Range

1 knot = 1.15 mph; 1 nm = 1.15 mile; 1 nm = 1.85 km

1 x 12" (305mm) /40 caliber Mark IX artillery gun (50 x 305mm projectiles carried).
4 x 18" (450mm) torpedo tubes in the bow (four reloads carried).
1 x 3" (76mm) Mk II HA Anti-Aircraft (AA) deck gun.

None.

Military lapel ribbon for the Cold War period

Military lapel ribbon for early warship designs

Military lapel ribbon for the Falklands War

Military lapel ribbon for the 1991 Gulf War

Military lapel ribbon for the Korean War

Military lapel ribbon representing modern aircraft

Military lapel ribbon for the Attack on Pearl Harbor

Military lapel ribbon for the Russian Invasion of Ukraine

Military lapel ribbon for the Vietnam War

Military lapel ribbon for the World War 1

Military lapel ribbon for the World War 2

Images

1 / 1

Image from the Public Domain.

Disclaimer | Privacy Policy | Cookies

2024 Military Pay Chart Military Ranks DoD Dictionary Conversion Calculators Military Alphabet Code Military Map Symbols

The "Military Factory" name and MilitaryFactory.com logo are registered ® U.S. trademarks protected by all applicable domestic and international intellectual property laws. All written content, illustrations, and photography are unique to this website (unless where indicated) and not for reuse/reproduction in any form. Material presented throughout this website is for historical and entertainment value only and should not to be construed as usable for hardware restoration, maintenance, or general operation. We do not sell any of the items showcased on this site. Please direct all other inquiries to militaryfactory AT gmail.com. No A.I. was used in the generation of this content; site is 100% curated by humans.

Part of a network of sites that includes GlobalFirepower, a data-driven property used in ranking the top military powers of the world, WDMMA.org (World Directory of Modern Military Aircraft), WDMMW.org (World Directory of Modern Military Warships), SR71blackbird.org, detailing the history of the world's most iconic spyplane, and MilitaryRibbons.info, cataloguing military medals and ribbons. Special Interest: RailRoad Junction, the locomotive encyclopedia.

©2023 www.MilitaryFactory.com • All Rights Reserved • Content ©2003-2023 (20yrs)