X class submarine
Encyclopedia
The X class was a World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 midget submarine
Midget submarine
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...

 class built for the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 during 1943–44.

Known individually as X-Craft, the vessels were designed to be towed to their intended area of operations by a full-size 'mother' submarine - (usually one of the T class
British T class submarine
The Royal Navy's T class of diesel-electric submarines was designed in the 1930s to replace the O, P and R classes. Fifty-three members of the class were built just before and during the Second World War, where they played a major role in the Royal Navy's submarine operations...

 or S class
British S class submarine (1931)
The S-class submarines of the Royal Navy were originally designed and built during the modernisation of the submarine force in the early 1930s to meet the need for smaller boats to patrol the restricted waters of the North Sea and the Mediterranean Sea replacing the British H class submarines...

) - with a passage crew on board, the operational crew being transferred from the towing submarine to the X-Craft by dinghy
Dinghy
A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...

 when the operational area was reached, the passage crew returning with the dinghy to the towing submarine. Once the attack was over, the X-Craft would rendezvous with the towing submarine and then be towed home. Range was limited primarily by the endurance and determination of their crews, but was thought to be up to 14 days in the craft or 1,500 miles (2,400 km) distance after suitable training. Actual range of the X-Craft itself was 500 nmi (926 km) surfaced and 82 nmi (151.9 km) at 2 knots (3.9 km/h) submerged.

Specification

The craft were about 51 feet (15.5 m) long, 5.5 feet (1.68 m) in maximum diameter and displaced 27 tons surfaced and 30 tons submerged. Propulsion was by a 4-cylinder Gardner 42 hp
Horsepower
Horsepower is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the...

 diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

, converted from a type used in London buses, and a 30 hp electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

, giving a maximum surface speed of 6.5 knots (12 km/h), and a submerged speed of 5.5 knots (10.1 km/h). The crew initially numbered three—commander, pilot and ERA—but soon a specialist diver
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....

 was added, for which an airlock
Airlock
An airlock is a device which permits the passage of people and objects between a pressure vessel and its surroundings while minimizing the change of pressure in the vessel and loss of air from it...

, known as a wet and dry compartment, was provided.

The X class submarines' weapons were two side-cargoes - explosive charges
Naval mine
A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

 held on opposite sides of the hull with two tons of amatol
Amatol
Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Its name originates from the words ammonium and toluene...

 in each. The intention was to drop these on the sea bed underneath the target then escape. The charges were detonated by a time fuse.

Service

A number of development craft were built before it was felt that a realistic weapon had been produced. The first operational craft was HMS X3 (or HM S/M X.3), launched on the night of March 15, 1942. Training with the craft began in September 1942, with HMS X4 arriving in October. In December 1942 and January 1943 six of the "5-10" class began to arrive, identical externally but with a completely reworked interior.

These operations were part of a longer series of frogman
Frogman
A frogman is someone who is trained to scuba diving or swim underwater in a military capacity which can include combat. Such personnel are also known by the more formal names of combat diver or combatant diver or combat swimmer....

 operations, see human torpedo
Human torpedo
Human torpedoes or manned torpedoes are a type of rideable submarine used as secret naval weapons in World War II. The basic design is still in use today; they are a type of diver propulsion vehicle....

.

Their first deployment was Operation Source
Operation Source
Operation Source was a series of attacks to neutralise the heavy German warships – Tirpitz, Scharnhorst and Lutzow – based in northern Norway, using X-class midget submarines....

 in September, 1943, an attempt to neutralise the heavy German
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 warships based in Northern Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

. Six X-Craft were used, but only 2 successfully laid charges (under the German battleship Tirpitz
German battleship Tirpitz
Tirpitz was the second of two s built for the German Kriegsmarine during World War II. Named after Grand Admiral Alfred von Tirpitz, the architect of the Imperial Navy, the ship was laid down at the Kriegsmarinewerft in Wilhelmshaven in November 1936 and launched two and a half years later in April...

); the rest were lost, scuttled
Scuttling
Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

 or returned to base. The Tirpitz was badly damaged and out of action until April 1944.

This was the only multiple X-craft attack. The lost craft were replaced early in 1944 with X20 to X25 and six training-only craft.

On April 15, 1944 HMS X24 attacked the Laksevåg
Laksevåg
Laksevåg is a borough of the city of Bergen, Norway.-Location:Laksevåg was separated from Askøy as a municipality of its own July 1, 1918. It was merged with Bergen January 1, 1972....

 floating dock
Floating dock
A floating dock is a platform or ramp supported by pontoons. It is usually joined to the shore with a ramp that rests upon the dock on rollers, to adjust for the vertical movement of the dock...

 at Bergen. X22 was intended for the mission, but had been accidentally rammed during training and sunk with all hands. The X24 made the approach and escaped successfully, but the charges were placed under the Bärenfels, a 7,500 ton merchant-vessel along the dock, which was sunk; the dock suffered only minor damage. On September 11, 1944 the operation was repeated by X24, with a new crew; this time the dock was sunk.
X-Craft were involved in the preparatory work for Overlord
Operation Neptune
The Normandy landings, codenamed Operation Neptune, were the landing operations of the Allied invasion of Normandy, in Operation Overlord, during World War II. The landings commenced on Tuesday, 6 June 1944 , beginning at 6:30 AM British Double Summer Time...

. Operation Postage Able
Operation Postage Able
Operation Postage Able was an X class submarine based Royal Navy operation in preparation for Overlord, the Allied invasion of Nazi-occupied Europe.-Intelligence gathering:...

 was planned to take surveys of the landing beaches with HMS X20 spending four days off the French coast. Periscope reconnaissance
Reconnaissance
Reconnaissance is the military term for exploring beyond the area occupied by friendly forces to gain information about enemy forces or features of the environment....

 of the shoreline and echo-soundings were performed during daytime. Each night, X20 would approach the beach and 2 divers would swim ashore. Soil samples were collected in condoms. The divers went ashore on two nights to survey the beaches at Vierville-sur-Mer
Vierville-sur-Mer
-External links:* *...

, Moulins St Laurent
Saint-Laurent-sur-Mer
Saint-Laurent-sur-Mer is a commune in the Calvados department in the Basse-Normandie region in northwestern France.-Population:-References:*...

 and Colleville-sur-Mer
Colleville-sur-Mer
Colleville-sur-Mer is a commune in the Calvados department in the Basse-Normandie region in northwestern France.The beach next to the coastal village was one of the principal beachheads during the Normandy landings on 6 June 1944, designated Omaha beach....

 in what became the American Omaha Beach
Omaha Beach
Omaha Beach is the code name for one of the five sectors of the Allied invasion of German-occupied France in the Normandy landings on 6 June 1944, during World War II...

. On the third night, they were due to go ashore off the Orne
Orne
Orne is a department in the northwest of France, named after the river Orne.- History :Orne is one of the original 83 departments created during the French Revolution, on March 4, 1790. It was created from parts of the former provinces of Normandy and Perche.- Geography :Orne is in the region of...

 Estuary (Sword Beach
Sword Beach
Sword, commonly known as Sword Beach, was the code name given to one of the five main landing areas along the Normandy coast during the initial assault phase, Operation Neptune, of Operation Overlord; the Allied invasion of German-occupied France that commenced on 6 June 1944...

), but by this stage fatigue (the crew and divers had been living on little more than benzedrine
Benzedrine
Benzedrine is the trade name of the racemic mixture of amphetamine . It was marketed under this brandname in the USA by Smith, Kline & French in the form of inhalers, starting in 1928...

 tablets) and the worsening weather caused Hudspeth to shorten the operation, returning to Dolphin
HMS Dolphin
Numerous Royal Navy vessels have been named HMS Dolphin after the dolphin.* The first seven Dolphins were small ketches and fireships., launched in 1731, was a 20-gun post ship, renamed Firebrand in 1755 and Penguin in 1757., launched in 1751, was a 24-gun post ship...

 on 21 January 1944. Hudspeth received a bar to his DSC
Distinguished Service Cross (United Kingdom)
The Distinguished Service Cross is the third level military decoration awarded to officers, and other ranks, of the British Armed Forces, Royal Fleet Auxiliary and British Merchant Navy and formerly also to officers of other Commonwealth countries.The DSC, which may be awarded posthumously, is...

.

X20 and X23 acted as lightships to help the D-Day
D-Day
D-Day is a term often used in military parlance to denote the day on which a combat attack or operation is to be initiated. "D-Day" often represents a variable, designating the day upon which some significant event will occur or has occurred; see Military designation of days and hours for similar...

 invasion fleet land on the correct beaches (Operation Gambit
Operation Gambit
During World War II Operation Gambit was a part of Operation Neptune, the landing phase of the invasion of northern France . Gambit involved two X class submarines which marked the extreme left and right limits of the British and Canadian invasion beaches with navigation lights and flags off...

), as part of the Combined Operations Pilotage Parties (COPP).

X24 is the only remaining intact example of an X-Craft. It can be found in the Royal Navy Submarine Museum
Royal Navy Submarine Museum
The Royal Navy Submarine Museum at Gosport is a museum tracing the international history of submarine development from the age of Alexander the Great to the present day, and particularly the history of the Submarine Service from the tiny Holland 1 to the nuclear powered Vanguard class submarine...

.

Operations continued in the Far East
Far East
The Far East is an English term mostly describing East Asia and Southeast Asia, with South Asia sometimes also included for economic and cultural reasons.The term came into use in European geopolitical discourse in the 19th century,...

 with the revised XE class submarine
XE class submarine
Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

s.

X-craft and crews

  • X3 — was lost on 4 November 1942 in Loch Striven due to a leaking engine valve. All crew escaped by utilizing their Davis Submerged Escape Apparatus
    Davis Submerged Escape Apparatus
    The Davis Submerged Escape Apparatus , was an early type of oxygen rebreather invented in 1910 by Sir Robert Davis, head of Siebe Gorman and Co. Ltd., inspired by the earlier Fleuss system...

    .
  • X5 — unofficially named Platypus, commanded by Lt. Henty-Creer RNVR (also the operation's commander), crew S-Lt. Nelson, Midshipman Malcolm, and ERA Mortiboys; passage crew Lt Terry-Lloyd (commanding), L/S Element, Stoker Garrity. Henty-Creer, Nelson, Malcolm, and Mortiboys were killed in the attack, though X5's exact fate is unknown.
  • X6 — named Piker II, commanded by Lt. Donald Cameron
    Donald Cameron (VC)
    Commander Donald Cameron VC was a Scottish recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. He is one of three VC winners from the small town of Carluke in South Lanarkshire...

    , crew Lt. J. T. Lorimer, S-Lt. R. Kendall, and ERA Goddard; passage crew Lt Wilson (commanding), Leading Seaman
    Leading Seaman
    Leading seaman is a junior non-commissioned rank or rate in navies, particularly those of the Commonwealth. When it is used by NATO nations, leading seaman has the rank code of OR-4. It is often equivalent to the army and air force rank of corporal and some navies use corporal rather than...

     McGregor, Stoker Oxley. Cameron earned a VC
    Victoria Cross
    The Victoria Cross is the highest military decoration awarded for valour "in the face of the enemy" to members of the armed forces of various Commonwealth countries, and previous British Empire territories....

    , Lorimer and Kendall DSO
    Distinguished Service Order
    The Distinguished Service Order is a military decoration of the United Kingdom, and formerly of other parts of the British Commonwealth and Empire, awarded for meritorious or distinguished service by officers of the armed forces during wartime, typically in actual combat.Instituted on 6 September...

    s, Goddard a Conspicuous Gallantry Medal
    Conspicuous Gallantry Medal
    The Conspicuous Gallantry Medal was, until 1993, a military decoration awarded to personnel of the British Armed Forces and formerly also to personnel of other Commonwealth countries, below commissioned rank, for conspicuous gallantry in action against the enemy at sea...

    .
  • X7 — unofficially named Pdinichthys, commanded by Lt. Basil C. G. Place
    Basil Charles Godfrey Place
    Rear Admiral Basil Charles Godfrey Place VC, CB, CVO, DSC was an English recipient of the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces....

    , crew S-Lt. R. Aitken, Lt. Whittam, and ERA Whiteley; passage crew Lt Philip (commanding), Leading Seaman J. Magennis
    James Joseph Magennis
    James Joseph Magennis VC was a Belfast-born recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces...

    , Stoker Luck. Vessel was scuttled immediately following the Tirpitz attack, but only Place escaped before she sank. Aitken escaped from the bottom of the fjord, but Whittam and Whiteley were unable to escape before their air gave out. Place also earned a VC, Aitken a DSO, while Philip earned an MBE
    Order of the British Empire
    The Most Excellent Order of the British Empire is an order of chivalry established on 4 June 1917 by George V of the United Kingdom. The Order comprises five classes in civil and military divisions...

    ;
  • X8 — commanded by Lt. McFarlane RAN
    Royal Australian Navy
    The Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...

     (Lt. Smart
    John Elliott Smart
    Lieutenant Commander John Elliott "Jack" Smart DSO OBE VRD was an officer in the Royal Navy commanding one of the midget submarines that attacked the German cruiser Lützow and the Japanese cruiser Takao during the Second World War.-Early life:Smart was born on 1 March 1916 in Northumberland in...

     was passage crew commander)
  • X9 — commanded by Lt. E. A. Kearon RNVR; A.H. Harte (Able Seaman) and G. H. Hollet (Stoker). X9 was unofficially named Pluto
  • X10 — unofficially named Excalibur, commanded by Lt. Hudspeth RANVR

Builders

The numbering sequence of the X class began with X3 because the designations X1 and X2 had already been used previously - X1
HM Submarine X1
HM Submarine X1 was conceived and designed as a submersible commerce raider for the Royal Navy; at the time of her launching she was the largest submarine in the world. The idea of a submarine cruiser had been proposed as early as 1915, but was not put into practice until 1921...

had been a one-off submarine cruiser
Cruiser
A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...

 design from the 1920s while X2
HM Submarine X2
HM Submarine X2 was an Italian Archimede-class submarine, originally named Galileo Galilei. She served in the Regia Marina before and during World War II, before her capture by the Royal Navy in 1940....

 had been assigned to a captured Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 submarine.
  • Prototypes
    • X3 — built by Varley Marine, Hamble
      Hamble-le-Rice
      Hamble-le-Rice is a village in the Borough of Eastleigh in Hampshire, UK. It is best known for being an aircraft training centre during the Second World War and is a popular yachting location...

      , scrapped 1945
    • X4 — built by Portsmouth Dockyard
      HMNB Portsmouth
      Her Majesty's Naval Base Portsmouth is one of three operating bases in the United Kingdom for the British Royal Navy...

      , scrapped 1945
  • X5-type
    • X5 — built by Vickers Armstrong
      Vickers Armstrong
      Vickers-Armstrongs Limited was a British engineering conglomerate formed by the merger of the assets of Vickers Limited and Sir W G Armstrong Whitworth & Company in 1927...

      , Barrow-in-Furness
      Barrow-in-Furness
      Barrow-in-Furness is an industrial town and seaport which forms about half the territory of the wider Borough of Barrow-in-Furness in the county of Cumbria, England. It lies north of Liverpool, northwest of Manchester and southwest from the county town of Carlisle...

      , used in Operation Source
      Operation Source
      Operation Source was a series of attacks to neutralise the heavy German warships – Tirpitz, Scharnhorst and Lutzow – based in northern Norway, using X-class midget submarines....

      , scuttled
      Scuttling
      Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

       Altenfjord 22 September 1943
    • X6 — built by Vickers, used in Operation Source, scuttled Altenfjord 22 September 1943
    • X7 — built by Vickers, used in Operation Source, scuttled Altenfjord 22 September 1943, salved 1976 for museum restoration
    • X8 — built by Vickers, used in Operation Source, scuttled in North Sea
      North Sea
      In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

       17 September 1943
    • X9 — built by Vickers, used in Operation Source, foundered under tow in North Sea 15 October 1943 with all hands
    • X10 — built by Vickers, used in Operation Source, scuttled in North Sea 3 October 1943
  • X20-type
    • X20 — built by Broadbent, Huddersfield
      Huddersfield
      Huddersfield is a large market town within the Metropolitan Borough of Kirklees, in West Yorkshire, England, situated halfway between Leeds and Manchester. It lies north of London, and south of Bradford, the nearest city....

      , used in Operation Gambit
      Operation Gambit
      During World War II Operation Gambit was a part of Operation Neptune, the landing phase of the invasion of northern France . Gambit involved two X class submarines which marked the extreme left and right limits of the British and Canadian invasion beaches with navigation lights and flags off...

    • X21 — built by Broadbent
    • X22 — built by Markham & Co.
      Markham & Co.
      Markham & Co. is an ironworks and steelworks company near Chesterfield, Derbyshire, England.- History :The Victoria Foundry near Chesterfield, Derbyshire was owned and successfully run by father and son partnership John and William Oliver from the mid-1850s until 1862 when, following the death of...

      , Chesterfield
      Chesterfield
      Chesterfield is a market town and a borough of Derbyshire, England. It lies north of Derby, on a confluence of the rivers Rother and Hipper. Its population is 70,260 , making it Derbyshire's largest town...

      , collided with HMS Syrtis and lost with all hands while training February 7, 1944
    • X23 — built by Markham, used in Operation Gambit, sold 1945
    • X24 — built by Marshall
      Marshall, Sons & Co.
      -External links:* – at the Powerhouse Museum, Sydney, Australia...

      , Gainsborough
      Gainsborough, Lincolnshire
      Gainsborough is a town 15 miles north-west of Lincoln on the River Trent within the West Lindsey district of Lincolnshire, England. At one time it served as an important port with trade downstream to Hull, and was the most inland in England, being more than 55 miles from the North...

      , attacked Laksevåg
      Laksevåg
      Laksevåg is a borough of the city of Bergen, Norway.-Location:Laksevåg was separated from Askøy as a municipality of its own July 1, 1918. It was merged with Bergen January 1, 1972....

       floating dock
      Floating dock
      A floating dock is a platform or ramp supported by pontoons. It is usually joined to the shore with a ramp that rests upon the dock on rollers, to adjust for the vertical movement of the dock...

       at Bergen, hulked 1945
    • X25 — built by Marshall, sold 1945
  • Training craft
    • XT1 — built by Vickers, scrapped 1945
    • XT2 — built by Vickers, scrapped 1945
    • XT3 — built by Vickers, scrapped 1945
    • XT4 — built by Vickers, scrapped 1945
    • XT5 — built by Vickers, scrapped 1945
    • XT6 — built by Vickers, scrapped 1945

Surviving examples

  • X24 - the only one to have seen service and survive is at the Royal Navy Submarine Museum
    Royal Navy Submarine Museum
    The Royal Navy Submarine Museum at Gosport is a museum tracing the international history of submarine development from the age of Alexander the Great to the present day, and particularly the history of the Submarine Service from the tiny Holland 1 to the nuclear powered Vanguard class submarine...

    , Gosport
    Gosport
    Gosport is a town, district and borough situated on the south coast of England, within the county of Hampshire. It has approximately 80,000 permanent residents with a further 5,000-10,000 during the summer months...

  • The remains of two XT-class craft are present on the beach at Aberlady Bay
    Aberlady Bay
    Aberlady Bay is a bay in East Lothian, Scotland between Aberlady and Gullane.In 1952, Aberlady Bay became the UK's first Local Nature Reserve and is served by the East Lothian Council Rangers....

     in East Lothian
    East Lothian
    East Lothian is one of the 32 council areas of Scotland, and a lieutenancy Area. It borders the City of Edinburgh, Scottish Borders and Midlothian. Its administrative centre is Haddington, although its largest town is Musselburgh....

    , Scotland
    Scotland
    Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

    . They were towed there in 1946 and moored to a large concrete block at the low tide level and were used as targets for aircraft. Much of the structure remains, semisubmerged in the sand, and can be reached at low spring tides.

In media

This type of midget submarine was portrayed in the 1955 war film, Above Us the Waves
Above Us the Waves (film)
Above Us the Waves is a 1955 war film directed by Ralph Thomas. It tells the story of human torpedo and midget submarine attacks on the German battleship Tirpitz. It is based on true-life attacks on the Tirpitz, first using manned torpedoes , and then the Royal Navy's midget X-Craft submarines in...

, featuring John Mills
John Mills
Sir John Mills CBE , born Lewis Ernest Watts Mills, was an English actor who made more than 120 films in a career spanning seven decades.-Life and career:...

, which was based on both Operation Source, and the earlier Chariot attacks on the Tirpitz.

This class of submarine was later featured in the 1968 movie Submarine X-1
Submarine X-1
Submarine X-1 is a 1969 British World War II war film loosely based on the Operation Source attack on the German battleship Tirpitz in 1943. In the film James Caan stars as Lt...

starring James Caan as a Canadian Royal Naval Volunteer Reserve officer who after losing his submarine and fifty crew members in a battle with a German ship during World War II, gets a second chance training crews to take part in a raid using midget subs.

See also

  • HM Submarine X1
    HM Submarine X1
    HM Submarine X1 was conceived and designed as a submersible commerce raider for the Royal Navy; at the time of her launching she was the largest submarine in the world. The idea of a submarine cruiser had been proposed as early as 1915, but was not put into practice until 1921...

     - World War 1 submarine.
  • HM Submarine X2
    HM Submarine X2
    HM Submarine X2 was an Italian Archimede-class submarine, originally named Galileo Galilei. She served in the Regia Marina before and during World War II, before her capture by the Royal Navy in 1940....

     - Name given to the Italian Submarine, Galileo Galilei, after she was captured and taken into service by the Royal Navy.
  • XE class submarine
    XE class submarine
    Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

     - Improved X Class submarine.
  • Stickleback class submarine
    Stickleback class submarine
    The Stickleback class submarines were midget submarines of the Royal Navy initially ordered as improved versions of the older XE class submarines...

    - Improved XE class submarine, in service in the 1950s.

External links

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