Editing British T-class submarine

{{Short description|Class of diesel-electric submarines}}
{{For|the [[US Navy]] submarine and single-build class of the same name|USS Triton (SSRN-586)}}
{{Use dmy dates|date=January 2017}}
{{Use British English|date=January 2017}}
{|{{Infobox ship begin
| sclass = 2
}}
{{Infobox ship image
| Ship image = HMS Thorn.jpg
| Ship caption = HMS ''Thorn''
}}
{{Infobox ship class overview
| Name = T class
| Builders =
| Operators = *{{navy|United Kingdom}}
* {{navy|Netherlands}}
* {{navy|Israel}}
| Class before = {{sclass|Grampus|submarine|4}}
| Class after = [[British U-class submarine|U class]]
| Subclasses =
| Cost =
| Built range =
| In service range =
| In commission range =
| Total ships building =
| Total ships planned =
| Total ships completed = 53
| Total ships cancelled =
| Total ships active =
| Total ships laid up =
| Total ships lost =
| Total ships retired =
| Total ships preserved =
}}
{{Infobox ship characteristics
| Hide header =
| Header caption =
| Ship class =
| Ship type = [[Submarine]]
| Ship displacement = *{{cvt|1290|LT|t|lk=on}} surfaced
* {{cvt|1560|LT|t}} submerged
| Ship length = {{convert|276|ft|6|in|m|abbr=on}}
| Ship beam = {{convert|25|ft|6|in|m|abbr=on}}
| Ship height =
| Ship draught = *{{convert|12|ft|9|in|m|abbr=on}} forward
* {{convert|14|ft|7|in|m|abbr=on}} aft
| Ship power =
| Ship propulsion =*Twin [[diesel engines]], {{cvt|1,250|hp|lk=on}} each
* Twin [[electric motors]], {{cvt|1,450|hp}} each
* Two shafts
| Ship speed = *{{convert|15.5|kn|lk=on}} surfaced
* {{convert|9|kn}} submerged
| Ship range = {{convert|8000|nmi|abbr=on|lk=on}} at {{convert|10|kn|abbr=on}} surfaced with 131 tons of fuel<ref name="Warship III p125">Warship III, T Class Submarines, Lambert, p125</ref>
| Ship endurance =
| Ship test depth =
| Ship complement = 48
| Ship time to activate =
| Ship sensors =
| Ship EW =
| Ship armament = *6 × bow [[torpedo tube]]s
* 4 × external torpedo tubes
** 16 [[torpedo]]es
* 1 [[QF 4-inch naval gun Mk IV, XII, XXII|QF 4-inch (100 mm)]] [[deck gun]]
| Ship notes =
}}
|}
The [[Royal Navy]]'s '''T class''' (or '''''Triton'' class''') of diesel-electric [[submarine]]s was designed in the 1930s to replace the [[Odin-class submarine|O]], [[Parthian-class submarine|P]], and [[Rainbow-class submarine|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. Four boats in service with the [[Royal Netherlands Navy]] were known as the [[Zwaardvisch-class submarine|'''''Zwaardvisch'' class''']].<ref name="Raven179">Raven (1988), p. 179.</ref>

At the start of the Second World War the T class was, with the British [[British S-class submarine (1931)|S]] and [[British U-class submarine|U class]], Dutch {{sclass|O 21|submarine|4}} and German [[Type VII submarine|Type VII]], one of the most advanced submarine classes in service.<ref>van den Pol (1989), p. 352.</ref>

In the decade following the war, the oldest surviving boats were scrapped and the remainder converted to anti-submarine vessels to counter the growing [[Cold War|Soviet submarine threat]]. The Royal Navy disposed of its last operational boat in 1969, although it retained one permanently moored as a static training submarine until 1974. The last surviving boat, serving in the [[Israeli Navy|Israel Sea Corps]], was scrapped in 1977.

==Development==
The design of what was to become the T class began in 1934 to create a replacement for the first British postwar submarines, the O, P and R classes. These similar classes of submarines had proved unsatisfactory, being mechanically unreliable, large, slow and over-complicated. The [[Washington Naval Treaty]] of 1922 required that these submarines be retired after 13 years of service.{{HMS|Oberon|P21|2}} would have to be paid off in August 1940 (the outbreak of war in 1939 kept her in service).{{sfnp|Kemp|1990|page=7}}

The 1930 [[London Naval Treaty]] restricted the British submarine fleet to a total tonnage of {{convert|52700|LT|t|lk=on}}, a maximum standard surfaced displacement of {{cvt|2000|LT}} for any boat, and maximum gun armament of {{convert|5.1|in|mm|abbr=on}}. The Americans had proposed a limit of {{cvt|1200|LT}} for the 1935 [[Second London Naval Treaty|London Disarmament Conference]], but this was rejected by the [[Admiralty (United Kingdom)|Admiralty]] since it would exclude the {{sclass|Grampus|submarine|0}} mine-laying submarines. The Admiralty proposed retaining the limit of {{cvt|2000|LT}}, hoping that the rival naval powers would build fewer but larger submarines as a matter of national pride, which would be easier to hunt than numerous smaller submarines.{{sfnp|Kemp|1990|page=9}} The [[National Government (United Kingdom)|National Government]] of [[Stanley Baldwin]] had also proposed banning the submarine altogether or imposing an individual displacement limit of {{cvt|250|LT}} but the Admiralty correctly predicted that the other nations would not accept such strict limitations and continued with the design of what was then known as the "Repeat P" or "Replace P" class of submarines.{{sfnp|Kemp|1990|page=9}}

The O, P, and R classes had been designed with the Pacific in mind as a counter to the [[Imperial Japanese Navy]]. In the absence of a battle fleet, the submarines would be the primary offensive weapon against the Japanese. The replacement "Repeat P" class had to have a similar endurance but be easier to maintain, as well as appreciably smaller in expectation of future treaty restrictions. In drawing up the requirements for the British submarine fleet, 20 of these new submarines were estimated to be required for a total tonnage of 20,000 tons.{{sfnp|Kemp|1990|page=9}} [[Rear Admiral Submarines|Rear Admiral (Submarines)]], [[Noel Laurence]], one of the most distinguished British submariners of the First World War, also pushed for a strong torpedo armament. He was convinced that a British submarine facing a powerful Japanese surface force would have difficulty penetrating the destroyer screen, and only a large torpedo salvo would be able to ensure the required hits at longer ranges, if necessary using only [[Asdic]] data for a firing solution.{{sfnp|Kemp|1990|page=9}}

On 27 February 1934, the [[Director of Naval Construction]] (DNC), Sir [[Arthur Johns (naval architect)|Arthur Johns]], was asked to investigate designs for a {{cvt|1000|LT}} displacement patrol submarine. The DNC designed (DNC 'A' and DNC 'B'), forming the basis of the November 1934 preliminary staff requirement. These designs called for an armament of six internal {{convert|21|in|adj=on}} [[torpedo tube]]s, two external tubes, and one {{convert|3|in|adj=on}} (or {{cvt|4|in|disp=comma}}, if stability permitted) gun, and a patrol capability of {{convert|4000|nmi}} at {{convert|11|kn}} plus sufficient fuel for a 28-day patrol, corresponding to a range of {{cvt|5500|nmi}} at {{convert|11|kn}}. Submerged endurance was to be 15 hours at {{convert|2|kn}} or eight hours at {{convert|5|kn}}. A maximum submerged speed of {{convert|9|kn}}, surfaced speed of {{convert|15|kn}} and diving depth of {{convert|300|ft}} were specified. An alternative proposal by Rear Admiral Laurence suggested using a [[double hull]] for greater survivability under [[depth charge]] attack but his proposal was rejected by the DNC in favour of a more conventional single hull with [[Saddle tank (submarine)|saddle tanks]].{{sfnp|Kemp|1990|pages=9–10}}

In 1935, the "Repeat P" design was modified to reduce the displacement to {{cvt|1000|LT}} in compliance with treaty limitations. Design 'C' had to sacrifice machinery space, reducing the surfaced speed to only {{cvt|14.5|kn}} and the surfaced endurance to {{cvt|8600|nmi}} at {{convert|8|kn}}. The design was again modified with Design 'D', eliminating fuel stowage in external tanks (which had proved prone to leakage on the O, P, and R classes) in favor of stowage within the pressure hull. It proved impossible to reduce the displacement to {{cvt|1000|LT}} without unacceptable reductions to endurance and the displacement was allowed to rise to {{cvt|1075|LT}}.{{sfnp|Kemp|1990|page=11}}

After a slight reduction in the length and the fresh water diving requirement of the design, the final design was agreed upon in May 1935. On 24 June 1935, the designation "Repeat P" was formally dropped by the Admiralty, and it was decided that the submarines would all bear names beginning with the letter T. Finally, on 3 September 1935, the name {{HMS|Triton|N15|2}} was selected for the [[lead ship]] of the class. Final approval for the design was given by the [[Admiralty Board (United Kingdom)|Admiralty Board]] on 13 February 1936. The [[Vickers Shipbuilding and Engineering|Vickers]], [[Cammell Laird]], and [[Scotts Shipbuilding and Engineering Company|Scotts]] shipbuilding companies were invited to submit tenders on 5 December 1935 and on 5 March 1936, the contract for ''Triton'' was awarded to Vickers Armstrong under the 1935 Programme.{{sfnp|Kemp|1990|page=12}}

== Design ==
The design of the T-class submarines was dictated by the requirements of an extremely large forward torpedo salvo capability and long patrol endurance for operations in the Pacific against Japanese warships, as well as the need to comply with treaty restrictions. These extremely challenging requirements led to many compromises in the design. Operational experience before and during the war led to many alterations and modifications to the class, and individual boats often differed noticeably from each other.

=== Hull and superstructure ===
To accommodate the external forward torpedo tubes, most of the T class had distinctive bulbous bows<!-- not the same as the "bulbous bow" of ships described in the article of the same name -->. The original bow shape of the Group One boats adversely affected the speed while surfaced and two of the Group One boats had the external bow tubes omitted during refitting ({{HMS|Triumph|N18|2}} and {{HMS|Thunderbolt|N25|2}}, formerly ''Thetis''), resulting in a finer bow shape.{{sfnp|Kemp|1990|page=18}} Group Two boats had the external bow tubes moved further back, allowing for a finer bow shape that ended the speed loss. They also had two of the external torpedo tubes reversed to face aft along with an additional rear torpedo tube, resulting in a characteristic hump.{{sfnp|Kemp|1990|page=19}} The final Group Three boats had the bows further fined and the casing around the conning tower and rear-facing torpedo tubes flattened, resulting in a smoother profile.{{sfnp|Kemp|1990|page=20}}

Pre-war T-class submarines were of riveted construction. The riveted hull proved remarkably strong, with many of the T-class boats exceeding the rated diving depth of {{convert|300|ft|abbr=on|0}} during combat. {{HMS|Tetrarch|N77|2}}, survived a dive to {{convert|400|ft|abbr=on|0}} on 23 April 1940.{{sfnp|Kemp|1990|page=22, 26}} Welding in the hull construction was officially sanctioned by the Admiralty, after much hesitation, in July 1942 for the pressure hulls of the Group Three boats, later extended to the entire hull. Welded hulls were considerably stronger, allowing a diving depth of {{convert|350|ft|m|abbr=on|0}} and for fuel to be carried in external [[ballast tank]]s for increased endurance. Partly welded Group Three boats had riveted external ballast tanks; these were welded up before being sent to the Far East to prevent telltale oil leaks betraying the submarine's presence.{{sfnp|Kemp|1990|page=21–22}} The estimated crush depth was {{convert|626|ft|m|abbr=on|0}}.{{sfnp|Brown|2000|p=119}}

The lead ship, ''Triton'', was completed with a very high open [[Bridge (nautical)|bridge]], which was very draughty. The following Group One boats had a slightly different bridge shape but these too were exposed, especially during heavy weather.{{sfnp|Kemp|1990|page=18}} Some of the Group One boats were fitted with cab-type bridges to resolve this problem, which were subsequently standardised in the Group Two boats. Wartime experience would eventually show that the greater visibility from the open bridges was more important in action than the better habitability of the cabs and the final Group Three boats reverted to the open bridge.{{sfnp|Kemp|1990|page=19}}

T-class boats had eleven main (ballast) tanks, two auxiliary tanks for adjusting trim, five compensating tanks for adjusting to changes in water density and the displacement of the submarine as stores were used up and the bow Q tank used for quick dives or rapid changes in depth. Two of the main tanks were converted into fuel tanks in the Group Three boats to increase endurance for operations in the Far East. Diving time from a 50 per cent buoyancy condition was good by British submarine standards at 30 seconds.{{sfnp|Kemp|1990|page=26}} The Group Two and Three boats had the fuel capacity increased on many boats to {{cvt|230|LT}}, giving a surfaced range of {{cvt|11000|nmi}} at {{cvt|10|kn}}.<ref name="Warship III p125" /><ref>Bishop, in ''The Complete Encyclopedia of Weapons of WW2'', p.450, gives 12,665nm at 10 knots.</ref>

=== Propulsion ===
The T-class boats used a variety of [[diesel engine]]s depending on where they were built. Vickers-built boats naturally used Vickers engines, while those from the [[Royal Navy Dockyard|Royal Dockyards]] used Admiralty diesel engines; Cammell Laird boats used [[Sulzer (manufacturer)|Sulzer]] engines, while the pre-war Scotts boats had German [[MAN SE|MAN]] supercharged diesel engines.{{sfnp|Kemp|1990|page=28}} These engines drove two shafts, each capable of {{convert|1,250|bhp|lk=in}} for a top surfaced speed of about {{convert|15|kn}}. The lead boat ''Triton'' achieved {{convert|16.29|kn}} on her first-of-class trials; this speed was never equalled by any of the other T-class boats, who usually managed about {{convert|14|–|15|kn}}.{{sfnp|Kemp|1990|page=27}}

The Vickers 6-cylinder 4-stroke {{cvt|1250|bhp}} injection diesel engines fitted to the majority of the T class proved to be very reliable engines, even if they were less advanced than the diesels used by the German [[U-boat]]s. The engine could continue running even if one cylinder failed by disconnecting the cylinder from the crankshaft. The 12 boats completed at the Royal Dockyards fitted with Admiralty diesel engines proved equally reliable, even though the engines were somewhat more complicated than the Vickers ones.{{sfnp|Kemp|1990|page=28}}

The MAN diesels proved to be rather troublesome; they were built under license, and once the Second World War broke out in 1939, technical support from the German MAN company stopped.{{sfnp|Kemp|1990|page=28}} By 1943, only two of the T-class boats with MAN engines were left ({{HMS|Tuna|N94|2}} and {{HMS|Tribune|N76|2}}), and they were relegated to training. Even when the Royal Navy in the Far East was facing a critical submarine shortage in March 1944, ''Tuna'' was rejected from being sent there due to her untrustworthy foreign engines.{{sfnp|Kemp|1990|page=30}} The Cammell Laird Sulzer 2-stroke engines received mixed reviews; some boats like {{HMS|Thrasher|N37|2}} and {{HMS|Thorn|N11|2}} were perfectly satisfactory, while the engines caused problems on others. They were insufficiently engineered for running at full speeds, and tended to crack the cylinder rings and blocks.{{sfnp|Kemp|1990|page=30}}

Submerged propulsion was provided by a 336-cell battery driving two {{cvt|1450|bhp|abbr=on}} Laurence Scott electric motors.{{sfnp|Kemp|1990|page=30}} These provided an endurance of 48 hours at {{convert|2.5|kn}} or only one hour at the maximum submerged speed of {{convert|9|kn}}.{{sfnp|Kemp|1990|page=30}} The battery proved vulnerable to shock damage from [[depth charge]] attacks, and this contributed to the loss of {{HMS|Tempest|N86|2}} in 1942. She sustained depth charge damage from the {{ship|Italian torpedo boat|Circe}} that ruptured her battery tank and filled the submarine with [[chlorine gas]], forcing her to surface and eventually surrender.{{sfnp|Greentree|2016|p=58}} This problem was resolved by strengthening the battery compartment and fitting rubber shock absorbers.{{sfnp|Kemp|1990|page=33}} In contrast with ''Tempest'', the modified {{HMS|Terrapin|P323|2}} survived a prolonged depth charge attack from Japanese escort vessels, which rendered her hull a [[constructive total loss]] but inflicted no damage to her battery cells whatsoever.{{sfnp|Kemp|1990|page=33}}

===Weaponry===

==== Torpedoes ====
It was expected from British work on ASDIC that other nations would develop something similar for submarine detection. In the face of expected enemy [[Anti-submarine warfare|anti-submarine]] measures any attack would probably have to be made at long range without the aid of the periscope, using only ASDIC. To counter the resulting inaccuracy, a large salvo of at least eight torpedoes would be needed.{{sfnp|Brown|2000|p=112}} British operational planning at the time also assumed that international treaties would prevent unrestricted submarine warfare, and the main purpose of the submarine would be to attack enemy warships. In such a situation, a commander may have only one chance to attack, so a large salvo was essential. The ten-torpedo salvo of the pre-war T-class boats was the largest ever fitted to any operational submarine.{{sfnp|Kemp|1990|page=36}}{{sfnp|McCartney|2006|p=8}}

All T-class submarines had six internal {{convert|21|in|mm|adj=on|0}} [[torpedo tube]]s in the bow. These were fitted with bow shutters on early Group One boats to reduce underwater drag; the benefits proved to be rather minimal, the shutters were prone to jamming from flotsam and the idea was dropped in favour of reshaping the torpedo tube orifices for minimal drag.{{sfnp|Kemp|1990|page=36}} After the loss of {{HMS|Thetis|N25|2}} due to the unintentional opening of the rear door of a torpedo tube while its bow cap was open, a special safety clip known as the "Thetis clip" was introduced to prevent the rear torpedo tube door from being opened by more than a fraction if the bow cap was not in place.{{sfnp|Kemp|1990|page=36}} Each T-class boat carried six reload torpedoes in the torpedo stowage compartment for the internal tubes. The reloading process was manual, although a power loading system was experimented with on ''Triumph'' in 1939 based on one developed on {{HMS|Grampus|N56|2}}. This system proved underpowered and the pressures of wartime production led to development being curtailed.{{sfnp|Kemp|1990|page=38}}

The internal torpedo tubes were complemented by four external ("E-type") 21-inch torpedo tubes on Group One T-class boats, all forward-facing. External tubes were used in order to avoid compromising the structural integrity of the pressure hull with too many openings. These tubes could not be reloaded from within the submarine, and it was also not possible to conduct maintenance on or withdraw the torpedo once it was loaded into the external tube. These tubes were angled downwards at a 5° bow angle to ease operations, except on the lead boat ''Triton''. Two of these external tubes were located in the bow, and another two located amidships at the base of the [[conning tower]].{{sfnp|Kemp|1990|page=38}} Unlike the internal tubes, the bow caps for the external tubes had to be worked manually, requiring a considerable amount of effort. The tubes also proved to be vulnerable to damage.{{sfnp|Kemp|1990|page=40}} Two of the T-class boats had their bow external tubes omitted during reconstruction: ''Thunderbolt'' (ex-''Thetis'') and ''Triumph''.{{sfnp|Kemp|1990|page=18}}

Prior to the outbreak of war, there had been much debate over the introduction of stern torpedo tubes on British submarines. The effectiveness of a two-torpedo stern salvo was considered to be doubtful and these tubes would take up valuable space on the submarine.{{sfnp|Kemp|1990|page=19}} Experience soon led to complaints from British submarine commanders like Commander [[Anthony Miers]] (''Torbay'') about the lack of stern torpedo tubes. Thus, eight of the Group One boats (''Taku'', ''Thunderbolt'', ''Tigris'', ''Torbay'', ''Tribune'', ''Trident'', ''Truant'', and ''Tuna'') were retrofitted with an eleventh external torpedo tube facing rearwards and this became standard on the Group Two boats onwards.{{sfnp|Kemp|1990|page=19}} On Group Two boats, the amidships torpedo tubes were also moved aft of the conning tower and reorientated towards the rear. Initially these were angled at 10° off the centerline but this created an area of flat casing that made maintaining depth difficult and for the last two Group Two boats (''Traveller'' and ''Trooper'') and all of the Group Three boats, the angle was reduced to 7°.{{sfnp|Kemp|1990|page=20}}

The primary torpedo used by the T-class submarines was the 21-inch [[British 21 inch torpedo#21 inch Mark VIII|Mark VIII]] torpedo, principally the Mark VIII** variant. This torpedo weighed {{cvt|1,566|kg}} with a {{cvt|365|kg}} [[Torpex]] warhead and used a Brotherhood burner-cycle engine for a range of {{cvt|4,570|m|yd}} at {{cvt|45.5|kn}} or {{cvt|6,400|m|yd}} at {{cvt|41|kn}}. It had a greater propulsive efficiency than any contemporary torpedo of a similar size but shortages of the Mark VIII early in the war led to some submarines using the older Mark IV.{{sfnp|Kemp|1990|page=41}} The Mark VIII was primarily fitted with a [[contact pistol]], which detonated the torpedo upon impact. A non-contact [[magnetic pistol]] known as the CCR (Compensated Coil Rod) was also developed and used during the war. Like the magnetic pistols developed by many other countries, the CCR gave endless trouble and was eventually withdrawn.{{sfnp|Kemp|1990|page=41}} Due to development problems with British postwar torpedoes, the Mark VIII would remain the standard torpedo used by the T class (and all Royal Navy submarines) until 1971 with the introduction of the [[British 21 inch torpedo#21 inch Mark 23 Grog|Mark 23]] wire-guided torpedo.{{sfnp|Kemp|1990|page=42}}

==== Deck guns ====
All T-class submarines, as built, were fitted with one {{convert|4|in|mm|adj=on|0}} deck gun as a weapon of surprise and self-defence. This was either the [[QF 4-inch naval gun Mk IV, XII, XXII|4-inch QF Mark XII or XXII]] (both interchangeable) on an S1 mounting. The mounting was located above the casing and forward of the conning tower, with a characteristic breastwork that rotated with the gun to provide room for the crew to operate the gun. No armour or overhead protection for the 4-inch gun crew was provided as built due to weight restrictions, except on ''Tabard'', ''Talent'', and ''Teredo''. Many other T-class boats received improvised [[gun shield]]s manufactured by [[depot ship]]s in the Far East, providing some degree of protection. The gun had a crew of five, and T-class submarines were initially allocated with 100 rounds of ammunition for the 4-inch gun. This proved insufficient and was soon increased; by the end of the war, T boats would often not carry reload torpedoes in favour of taking more gun ammunition.

The standard anti-aircraft armament carried by T-class submarines was three .303-inch machine guns. These were initially [[Lewis gun]]s, but from 1941 onward replaced with the better [[Vickers K machine gun|Vickers]] gas-operated (VGO) machine gun. The Vickers was sometimes substituted with the [[Bren light machine gun|Bren gun]] if supplies could be spared from the [[British Army during the Second World War|Army]]. Later, most T-class boats were retrofitted or completed with the ubiquitous [[Oerlikon 20 mm cannon|20 mm Oerlikon]]. This was located aft of the conning tower. Most T-class boats were fitted with only one, but ''Tantivy'' carried two 20&nbsp;mm cannon side by side on pedestal mountings, while ''Tireless'' was completed with a twin Oerlikon Mark 12A mounting. The crew of ''Terrapin'' was able to acquire a [[M2 Browning|.50 inch Browning air-cooled machine gun]] on their own initiative, but this weapon was too powerful for the conning tower's brass structure (brass being used instead of steel to prevent any interfering with the magnetic compass), and was eventually dropped.

==Service history==

=== Prewar ===
The lead boat of the class, ''Triton'', was commissioned on 9 November 1938. She would be joined by another 14 T-class submarines ordered under the prewar 1936–1938 Programmes. The unfortunate loss of {{HMS|Thetis|N25|2}} on 1 June 1939 along with 99 of the men on board during her trials led to modification of the Royal Navy's submarine escape procedures. ''Triton'' was the only member of the class to undergo full trials, for the outbreak of war meant that the Royal Navy could not afford this luxury at a time when modern submarines were desperately needed. When war broke out on 1 September 1939, there were only three T-class boats in service: ''Triton'', ''Triumph'' and ''Thistle''.

=== Second World War ===
[[File:British Triton-class submarines in Service.png|thumb|Number of British T-class submarines in service by year in World War II]]
As the Royal Navy's standard ocean patrol submarine, the T-class submarines were heavily engaged during World War II, from the North Sea to the Mediterranean, and finally the Far East.

The nature of the British submarine campaign against Germany during the early stages of the war was very different from that of the German submarine campaigns in the Atlantic and the later American submarine campaign in the Pacific. Germany did not depend on heavy mercantile traffic the way Britain was dependent on overseas trade, and thus there were no unprotected [[convoy]]s or mercantile traffic for the British submarines to ravage. Most German mercantile traffic was confined to the [[North Sea]], which was heavily [[Naval mine|mined]]. Thus, British submarines were obliged to undertake long, often fruitless patrols in these confined, dangerous waters.

==== Norway ====
[[File:On Board HM Submarine Tribune, 1942 TR491.jpg|thumb|On board {{HMS|Tribune|N76|6}} in 1942]]
On 10 September 1939, nine days after the war began, ''Triton'' sighted another submarine while on patrol off the coast of Norway. When the submarine failed to respond to challenges, she fired two torpedoes from the external bow tubes, hitting the submarine with one and sinking it. Unfortunately, this submarine turned out to be {{HMS|Oxley}}, the first British submarine to be lost during the war, with only two of her crew surviving the attack. The crew of the ''Triton'' was exonerated by a subsequent inquiry, but it was an inauspicious start to the war for the T-class submarine fleet. ''Triumph'' was unfortunate enough to run into a mine on 26 December 1939 that blew off her bow section, but miraculously survived and was able to return to Rosyth for extensive repairs.

With the start of the [[Norwegian Campaign]] in April 1940, increased ''[[Kriegsmarine]]'' traffic in support of the German invasion led to more action for the T-class submarines based in the North Sea. On 8 April 1940, ''Triton'' encountered the German [[cruiser]]s {{ship|German cruiser|Blücher||2}} and ''[[German cruiser Deutschland|Lützow]]'' but missed with a full salvo of ten torpedoes. Two days later, she had more success after reloading, sinking three ships in a German convoy with six torpedoes. ''Truant'' also achieved a notable success, hitting and disabling the cruiser {{ship|German cruiser|Karlsruhe||2}}, which had to be finished off by an escorting [[torpedo boat]]. Two T-class boats were lost during the Norwegian campaign: {{HMS|Thistle|N24|2}} (torpedoed by {{GS|U-4|1935|2}} on 10 April 1940) and {{HMS|Tarpon|N17|2}} (depth-charged by the [[Q-ship]] ''Schiff 40''/''Schürbek'' on 14 April 1940).

==== Bay of Biscay ====
The British began establishing submarine patrols in the strategic [[Bay of Biscay]], known as the 'Iron Ring', in July 1940 after the [[Battle of France|fall of France]] and the German occupation of the French Atlantic ports. These became much more important once heavy German warships like {{ship|German battleship|Scharnhorst||2}}, {{ship|German battleship|Gneisenau||2}}, and {{ship|German cruiser|Prinz Eugen||2}} arrived there in 1941.

On 15 December 1940, ''Thunderbolt'' torpedoed the Italian submarine {{ship|Italian submarine|Capitano Tarantini||2}}, the first of eventually 14 [[Axis powers|Axis]] submarines to fall victim to T-class submarines. On 5 July 1941, ''Tigris'' accounted for another Italian submarine, the {{ship|Italian submarine|Michele Bianchi||2}}. The 'Iron Ring' patrols were discontinued after the infamous [[Channel Dash]] in February 1942.

==== Mediterranean ====
T-class submarines began to operate in the [[Mediterranean and Middle East theatre of World War II|Mediterranean]] from September 1940 onward. This was the theatre in which the T class were most heavily engaged in operations and correspondingly suffered proportionately heavy losses.

Operations in the Mediterranean posed several substantial challenges for British submarines and the T class in particular. Firstly, the Italian ''[[Regia Marina]]'', almost uniquely among the Axis navies, had devoted a substantial amount of resources and training to anti-submarine warfare. Equipped with their own version of [[sonar]], the ''ecogoniometro'' (ECG), possessing excellent escort vessels, and making extensive use of mines, the Italians were to prove the most successful of the Axis powers at destroying Allied submarines.

The Mediterranean Sea was also characterised by calm, shallow, and unusually clear waters compared to the North Atlantic. Submarines could often be spotted from the air even when submerged, and the shallow waters made deep diving to escape attack difficult or downright impossible. Having been designed for operations in the Far East, the T boats were substantially larger than the standard German [[Type VII submarine|Type VII U-boat]], and thus they were more vulnerable to detection and mines.

Conversely, the large sizes of the T-class boats gave them substantially greater endurance and range compared to the smaller standard Royal Navy submarines like the [[British S-class submarine (1931)|S]] and [[British U-class submarine|U]] classes. This allowed them to operate successfully from the British bases of [[Alexandria]] and [[Gibraltar]], which were located at considerable distances from Axis waters.

The British submarine campaign in the Mediterranean was primarily targeted at Axis convoys from Italy to North Africa supplying the [[Royal Italian Army during World War II|Italian army]] and German [[Afrika Korps]] fighting the [[Eighth Army (United Kingdom)|British Commonwealth forces]] in [[North African Campaign|North Africa.]] Axis air power made it extremely hazardous to use surface warships in this role, and until the Allies were able to establish air superiority over [[Malta]] the burden of the anti-shipping campaign would fall on the submarines based in the Mediterranean. British submarines did not operate surfaced during the day in the Mediterranean as it was far too hazardous thanks to Axis air power, surfacing to recharge only at night. By contrast, Axis submarines tended to operate surfaced in broad daylight, a habit described by British submariners as 'truly reprehensible'. T-class submarines thus proved especially successful against Axis submarines in the theatre, accounting for five Italian submarines for no losses to British submarines.

Thirteen T-class submarines were lost during the Mediterranean campaign, including all but two of the Group Two boats. Over half of these (seven) were lost to Axis minefields. In return, they played a crucial role in denying supplies to the Axis forces in North Africa, which ultimately led to Allied victory in that theatre. For example, ''Turbulent'' accounted for over 90,000 tons of Axis shipping.

Four Victoria Crosses (VCs) were awarded to T-class submarine crews during the Mediterranean campaign. One, awarded to [[John Linton|J. W. Linton]], captain of ''Turbulent'', was unusual in that it was awarded for sustained effort and not for outstanding bravery in a single action. The other two were awarded to two crew members of ''Thrasher'', [[Thomas William Gould|T. W. Gould]] and [[Peter Scawen Watkinson Roberts|P. S. W. Roberts]], who removed two unexploded anti-submarine bombs stuck in the submarine's gun casing. ''Thrasher'' remains the only British submarine in history to have had more than one VC recipient among her crew. The last VC was awarded to [[Anthony Miers|A. Miers]], captain of ''Torbay'', for a daring raid penetrating into [[Corfu]] harbour.

=== Far East and Indian Ocean ===
Despite the class being built with operations against the Japanese in mind not a single T class (or any operational British submarine) was left in the theater at the time of the Japanese attack. {{HMS|Truant||2}} and {{HMS|Trusty|N45|2}} were ordered to the area with haste but arrived just in time for [[Battle of Singapore|Singapore to fall]]. Following the allied retreat they were based in [[Sri Lanka|Ceylon]] with the surviving Dutch submarines. They were sortied to intercept the expected Japanese route for the [[Indian Ocean raid|Indian Ocean Raid]], and ''Truant'' did sink two [[Imperial Japanese Army]] transports, but the [[1st Air Fleet|Kido Butai]] did not pass that way.

This small flotilla was all that were available until late 1943 when new S and T-class boats started to arrive. These new arrivals had modifications for better performance in the warmer climates and were better suited for offensive operations. Given Japan's need to defend against the American advance, high value targets were limited, though there were some notable successes: {{HMS|Tally-Ho||2}} sank the {{ship|Japanese cruiser|Kuma||2}} and the German-manned ''UIT-23'', Taurus'' sank the {{Jsub|I-34}}, {{HMS|Telemachus|P321|2}} the Japanese submarine ''[[Kaidai-type submarine|I-166]]'' and {{HMS|Trenchant|P331|2}} the {{GS|U-859}} and Japanese heavy cruiser {{ship|Japanese cruiser|Ashigara||2}}. {{HMS|Tantalus|P318|2}} became the only British ship to sight Japanese capital units when she spotted the Japanese [[battleship]]s {{ship|Japanese battleship|Ise||2}} and {{ship|Japanese battleship|Hyūga||2}} during [[Operation Kita]], but was unable to attack.

Though targets of opportunity were poor compared to where US submarines were operating the class performed reasonably well, sinking numerous merchant/cargo ships and smaller Japanese warships along with large numbers of coasters and small vessels. They proved better suited for Far Eastern operations than the smaller S class, having greater crew comfort and range.

=== Postwar ===
After the war, all surviving Group One and Two boats were scrapped and the remainder fitted with [[Submarine snorkel|snorts]].

In the late 1940s and 1950s, most were streamlined for quiet and higher-speed underwater operation against [[Soviet Union|Soviet]] submarines, in place of the anti-surface-ship role that they had been designed for. In January 1948, it was formally acknowledged that the main operational function of the British submarine fleet would now be to intercept Soviet submarines slipping out of their bases in Northern Russia to attack British and Allied merchant vessels. The following April, the Assistant Chief of Naval Staff, Rear-Admiral [[Geoffrey Oliver]], circulated a paper in which he proposed that British submarines take a more offensive role by attacking Soviet submarines off the Northern Russian coast and mining the waters in the area. With the dramatically reduced surface fleet following the end of the Second World War, he commented that this was one of the few methods the Royal Navy had for "getting to the enemy on his home ground."{{sfnp|Kemp|1990|page=127}}

Much of the work carried out on the submarines was underpinned by results of measurements made using {{HMS|Tradewind||2}}, which had been modified in July 1945 – September 1946 to become an acoustic trials submarine, with external tubes and guns removed, the bridge faired, the hull streamlined and some internal torpedo tubes blanked over.

Starting in 1948, eight newer all-welded boats underwent extensive "Super-T" conversion at [[Chatham Dockyard]]. The modifications included the removal of deck guns and the replacement of the conning tower with a "fin", a smooth-surfaced and far more symmetrical and streamlined tower. An extra battery was installed, and a new section of hull inserted to accommodate an extra pair of motors and switchgear. This varied between {{convert|14|ft|m}} in the earlier conversions and {{convert|17|ft|6|in|m}} in the later ones. These changes allowed an underwater speed of {{convert|15|kn}} or more and increased the endurance to around 32 hours at {{convert|3|kn}}. The first boats to undergo this modification were {{HMS|Taciturn|P334|2}} in November 1948 – March 1951, followed by {{HMS|Turpin|P354|2}} in June 1949 – September 1951. The programme was completed with the conversion of {{HMS|Trump|P333|2}} in February 1954 – June 1956.

The conversion was not entirely successful since the [[metacentric height]] was reduced, making the boats roll heavily on the surface in rough weather. This was alleviated in 1953 in those conversions which had been completed by increasing the buoyancy by raising the capacity of a main ballast tank by 50 tons. This was done by merging it with an existing emergency oil fuel tank. For the four boats remaining to be converted, increase in buoyancy was achieved by lengthening the extra hull section to be inserted from {{convert|14|ft|m}} to {{convert|17|ft|6|in|m}}. The effect was to lengthen the control room and strict instructions were issued that this space was not to be used for extra equipment otherwise the improved buoyancy would be affected.

In the meantime, in December 1950, approval was given for the streamlining of five riveted boats. This was a much less extensive process, with the removal of deck guns and external torpedo tubes, the replacement of the conning tower by a "fin" and replacement of the batteries by more modern versions providing a 23 per cent increase in power. The work was much more straightforward than the conversion of the welded boats and was undertaken during normal refit. The first riveted boat to undergo this modification was {{HMS|Tireless|P327|2}} in 1951.

The last operational Royal Navy boat of the class was {{HMS|Tiptoe|P332|2}}, which was decommissioned on 29 August 1969. The last T-class boat in service with Royal Navy, albeit non-operationally, was {{HMS|Tabard|P342|2}}, which was permanently moored as a static training submarine at the shore establishment {{HMS|Dolphin|shore establishment|6}} from 1969 until 1974, when she was replaced by {{HMS|Alliance|P417|6}}.

The last operational boat anywhere was the INS ''Dolphin'', formerly {{HMS|Truncheon|P353|6}}, one of three T-class boats (and two S-class ones) sold to the [[Israeli Navy]];<ref>{{cite web  | url= http://submarines.dotan.net/tclasse/ | title = Israeli T-class submarines | work = Israeli Submarines | access-date = 2006-10-29}}</ref> it was decommissioned in 1977.

Another submarine sold to Israel, {{HMS|Totem|P352|2}} renamed {{INS|Dakar}}, was lost in the Mediterranean in 1969 while on passage from [[Scotland]] to [[Haifa]]. Although the wreck was discovered in 1999, the cause of the accident remains uncertain.

==Group One boats==
These fifteen pre-war submarines were ordered under the Programmes of 1935 ({{HMS|Triton|N15|2}}), 1936 (next four), 1937 (next seven) and 1938 (last three). The boats originally had a bulbous bow covering the two forward external torpedo tubes, which quickly produced complaints that they reduced surface speed in rough weather. These external tubes were therefore removed from ''Triumph'' during repairs after she was damaged by a [[naval mine|mine]] and ''Thetis'' during the extensive repairs following her sinking and subsequent salvage. Only six survived the war, less than half.
* [[HMS Triton (N15)|''Triton'']] sunk in the [[Adriatic Sea]] on 18 December 1940
* [[HMS Thetis (N25)|''Thetis'']] built at Cammell Laird. Sank during trials in 1939 with 99 dead. ''Thetis'' was salvaged and recommissioned as [[HMS Thunderbolt (N25)|''Thunderbolt'']] in October 1940. Sunk by the Italian corvette [[Gabbiano-class corvette|''Cicogna'']] off [[Strait of Messina]] on 14 March 1943)
* [[HMS Tribune (N76)|''Tribune'']], built at Scotts, Greenock, commissioned October 1939, scrapped 1947
* [[HMS Trident (N52)|''Trident'']] built at Cammell Laird, commissioned October 1939, scrapped 1946
* [[HMS Triumph (N18)|''Triumph'']] built by Vickers, Barrow-in-Furness and commissioned May 1939. Lost, probably to Italian mines, on 14 January 1942
* [[HMS Taku (N38)|''Taku'']] scrapped 1946
* [[HMS Tarpon (N17)|''Tarpon'']] (probably sunk by German minesweeper ''M-6'' on 14 April 1940)
* [[HMS Thistle (N24)|''Thistle'']] torpedoed by [[German submarine U-4 (1935)|''U-4'']] on 10 April 1940 off Norway
* [[HMS Tigris (N63)|''Tigris'']] (probably sunk by German ship [[German warship Uj-2210|''UJ-2210'']] on 27 February 1943)
* [[HMS Triad (N53)|''Triad'']] sunk by gunfire from the {{ship|Italian submarine|Enrico Toti|1928|6}} in the [[Gulf of Taranto]] on 15 October 1940
* [[HMS Truant (N68)|''Truant'']] wrecked 1946 on way to breakers
* [[HMS Tuna (N94)|''Tuna'']] scrapped 1946
* [[HMS Talisman (N78)|''Talisman'']] lost in Mediterranean, probably to Italian mines, on 17 September 1942)
* [[HMS Tetrarch (N77)|''Tetrarch'']], commissioned February 1940 the only boat completed with mine laying equipment. Lost in Mediterranean, probably to Italian mines, after 27 October 1941.
* [[HMS Torbay (N79)|''Torbay'']] built at Chatham, commissioned 1941, scrapped 1947.

==Group Two boats==
These seven vessels were all ordered under the 1939 War Emergency Programme. The first, ''Thrasher'', was launched on 5 November 1940. The external bow torpedo tubes were moved seven feet aft to help with sea keeping. The two external forward-angled tubes just forward of conning tower were repositioned aft of it and angled backwards to fire astern, and a stern external torpedo tube was also fitted. This gave a total of eight forward-facing tubes and three rear-facing ones. All Group Two boats were sent to the [[Mediterranean]], only ''Thrasher'' and ''Trusty'' returned.
* [[HMS Tempest (N86)|''Tempest'']] (sunk by the Italian {{sclass|Spica|torpedo boat}} [[Italian torpedo boat Circe|''Circe'']] on 13 February 1942)
* [[HMS Thorn (N11)|''Thorn'']] (sunk by the Italian {{sclass|Orsa|torpedo boat}} [[Italian torpedo boat Pegaso (1936)|''Pegaso'']] on 6 August 1942)
* [[HMS Thrasher (N37)|''Thrasher'']]
* [[HMS Traveller (N48)|''Traveller'']] (lost, probably to Italian mines, on 12 December 1942)
* [[HMS Trooper (N91)|''Trooper'']] (lost, probably to German mines, on 14 October 1943)
* [[HMS Trusty (N45)|''Trusty'']]
* [[HMS Turbulent (N98)|''Turbulent'']] (possibly sunk by an Italian torpedo boat, or a mine in March 1943<ref>[http://uboat.net/allies/warships/ship/3505.html "HMS ''Turbulent'' (N 98)"]</ref>) During her career, she sank over 90,000 tons of enemy shipping.<ref>[http://www.royalnavy.mod.uk/server/show/nav.2558 Submarine History : Submarine Service : Operations and Support : Royal Navy<!-- Bot generated title -->] {{webarchive |url=https://web.archive.org/web/20070220000000/http://www.royalnavy.mod.uk/server/show/nav.2558 |date=20 February 2007 }}</ref>

==Group Three boats==
[[File:HMS Totem Sep 17 1945 SLV.jpg|thumb|300px|HMS ''Totem'' in September, 1945]]
Wartime austerity meant that they lacked many refinements such as [[jackstaff]]s and guardrails, and had only one anchor. Much of the internal pipework was steel rather than copper. The first Group Three boat was ''P311'', launched on 10 June 1942. Welding gradually replaced riveting and some boats were completely welded, which gave them an improved rated maximum diving depth of 350&nbsp;ft (107 m).<ref>Barrow-in-Furness Branch of the Submariners Association. HMS ''Tabard''.</ref>
{{Clear}}
{{Col-begin}}
{{Col-break}}
'''Nine submarines were ordered under the 1940 Programme;'''
* [[HMS P311|''P311'']] (lost, probably to Italian mines, before her name ''Tutankhamen'' was formally assigned)
* [[HMS Trespasser (P312)|''Trespasser'']]
* [[HMS Taurus (P399)|''Taurus'']] (to the Royal Netherlands Navy as [[HNLMS Dolfijn (1948)|''Dolfijn'']])
* [[HMS Tactician (P314)|''Tactician'']]
* [[HMS Truculent (P315)|''Truculent'']] (sunk in collision on 12 January 1950)
* [[HMS Templar (P316)|''Templar'']]
* [[HMS Tally-Ho (P317)|''Tally-Ho'']]
* [[HMS Tantalus (P318)|''Tantalus'']]
* [[HMS Tantivy (P319)|''Tantivy'']]
{{Col-break}}
'''Seventeen submarines were ordered under the 1941 Programme;'''
* [[HMS Telemachus (P321)|''Telemachus'']]
* [[HMS Talent (P322)|''Talent'' (P322)]] (to the [[Royal Netherlands Navy]] as [[HNLMS Zwaardvisch (P322)|''Zwaardvisch'']])
* [[HMS Terrapin (P323)|''Terrapin'']]
* [[HMS Thorough (P324)|''Thorough'']]
* [[HMS Thule (P325)|''Thule'']]
* [[HMS Tudor (P326)|''Tudor'']]
* [[HMS Tireless (P327)|''Tireless'']]
* [[HMS Token (P328)|''Token'']]
{{Col-break}}
* [[HMS Tradewind|''Tradewind'']]
* [[HMS Trenchant (P331)|''Trenchant'']]
* [[HMS Tiptoe (P332)|''Tiptoe'']]
* [[HMS Trump (P333)|''Trump'']]
* [[HMS Taciturn (P334)|''Taciturn'']]
* [[HMS Tapir (P335)|''Tapir'']] (to the Royal Netherlands Navy as [[HNLMS Zeehond (2)(P335)|''Zeehond'' (2)]])
* [[HMS Tarn (P336)|''Tarn'']] (to the Royal Netherlands Navy as [[HNLMS Tijgerhaai (P336)|''Tijgerhaai'']])
* [[HMS Talent (P337)|''Talent'' (P337)]]
* [[HMS Teredo (P338)|"Teredo"]]
{{Col-end}}

'''Fourteen submarines were ordered under the 1942 Programme, but only five were completed;'''
* [[HMS Tabard (P342)|''Tabard'']]
* [[HMS Totem (P352)|''Totem'']] (lost in accident on passage to Israel as [[INS Dakar|INS ''Dakar'']])
* [[HMS Truncheon (P353)|''Truncheon'']] (later the Israeli INS ''Dolphin'')
* [[HMS Turpin (P354)|''Turpin'']] (later the Israeli INS ''Leviathan'')
* [[HMS Thermopylae (P355)|''Thermopylae'']]

The other nine were ordered but cancelled on 29 October 1945 following the end of hostilities:
* ''Thor'' (P349) (laid down at [[Portsmouth|Portsmouth Dockyard]] on 5 April 1943 and launched on 18 April 1944. However, the [[Second World War|war]] ended before she was completed and she was sold for scrapping to Rees Shipbreaking Co Ltd of [[Llanelli]], [[Wales]] in July 1946.<ref>[http://uboat.net/allies/warships/ship/3380.html HMS ''Thor''], Uboat.net</ref> She would have been the only ship of the Royal Navy to bear the name ''Thor'', after the mythological [[Thor|Norse god of thunder]].
* [[HMS Tiara (P351)|''Tiara'']] (also launched on 18 April 1944 at Portsmouth but not completed)
* ''Theban'' (P341)
* ''Talent'' (P343)
* ''Threat'' (P344)
* also four unnamed submarines (P345, P346, P347 and P348).

==Transfers to Royal Netherlands Navy==
Four submarines were transferred to the Royal Netherlands Navy in the 1940s were they formed the [[Zwaardvisch-class submarine|''Zwaardvisch'' class]].<ref name="Raven179" /><ref name="Jalhay122124">Jalhay (1982), pp. 122-124.</ref> Two were later returned in 1953.<ref name="Jalhay122124" />
* [[HNLMS Tijgerhaai (P336)|''Tijgerhaai'']] (ex-[[HMS Tarn (P336)|''Tarn'']]): transferred 1944
* [[HNLMS Zwaardvisch (P322)|''Zwaardvisch'']] (ex-[[HMS Talent (P322)|''Talent'']]): transferred 1943
* [[HNLMS Zeehond (2)(P335)|''Zeehond'' (2)]] (ex-[[HMS Tapir (P335)|''Tapir'']]): transferred 1948, returned 1953
* [[HNLMS Dolfijn (1948)|''Dolfijn'']] (ex-[[HMS Taurus (P399)|''Taurus'']]): transferred 1948, returned 1953

==Transfers to the Israeli Navy==
Three submarines were sold to the Israeli Navy in the 1960s. ''Totem'', renamed ''Dakar'', was lost in transit in 1968.
* [[INS Dakar|INS ''Dakar'']] (ex-[[HMS Totem (P352)|''Totem'']]): sold 1965, commissioned 1967; lost January 1968.
* [[INS Dolphin (1944)|INS ''Dolphin'']] (ex-[[HMS Truncheon (P353)|''Truncheon'']]): sold 1968
* [[INS Leviathan (1943)|INS ''Leviathan'']] (ex-[[HMS Turpin (P354)|''Turpin'']]): sold 1965, commissioned 1967

==Notes==
{{Reflist}}

==References==
{{Commons}}
* {{cite book
  |last=Akermann  |first=Paul
  |title=Encyclopaedia of British Submarines 1901–1955|edition=reprint of the 1989|year=2002
  |publisher=Periscope Publishing|location=Penzance, Cornwall|isbn=1-904381-05-7
  |ref={{SfnRef|Akermann|1989}}
}}
* {{cite book
  |last=Bagnasco |first=Erminio |title=Submarines of World War Two |year=1977
  |publisher=Naval Institute Press |location=Annapolis, Maryland |isbn=0-87021-962-6
}}
* {{Cite book
  |title=Nelson to Vanguard
  |first=D. K.  |last=Brown
  |publisher=Chatham Publishing
  |year=2000
  |isbn=1-86176-136-8
}}
* Clayton, Tim (2011). ''Sea Wolves''. London. Abacus. {{ISBN|978-0-349-12289-2}}
* {{Cite Colledge2006}}
* {{cite book
  |title=Conway's All the World's Fighting Ships 1922–1946|editor1-last=Chesneau|editor1-first=Roger
  |publisher=Conway Maritime Press|location=Greenwich, UK|year=1980|isbn=0-85177-146-7
  |ref={{SfnRef|Conway's All the World's Fighting Ships}}
}}
* {{Cite book
  |title=British submarine vs Italian torpedo boat : Mediterranean 1940-43
  |last=Greentree  |first=David
  |publisher=Osprey Publishing  |location=Oxford
  |year=2016
  |isbn=978-1472814128
  |oclc=952159340
}}
* {{cite book
  |last=Kemp  |first=Paul J.
  |title=The T-class Submarine: The Classic British Design
  |publisher=Naval Institute Press|location=Annapolis, Maryland|year=1990|isbn=1-55750-826-7
  |oclc=22575300
}}
* [[Alastair Mars|Mars, Alistair]] (1971). ''British Submarines at War 1939-1945''. London. William Kimber. {{ISBN|0-7183-0202-8}}
* {{cite book
  |last=McCartney  |first=Innes|location=Oxford, UK|title=British Submarines 1939–1945
  |series=New Vanguard|volume=129|year=2006|publisher=Osprey|isbn=1-84603-007-2
}}
* {{cite magazine |last=van den Pol |first=E. |date=1989 |title=Aspects of submarines - Part I: Some notes on development|magazine=Schip en Werf|location=Rotterdam |publisher=Wyt & Zonen |volume=56|issue=10|issn= 0036-6099|pages=352-358}}
* {{cite book |last=Jalhay |first=P.C. |date=1982 |title=Nederlandse Onderzeedienst 75 jaar |language=Dutch |edition= |url= |location=Bussum |publisher=De Boer Maritiem |page= |isbn=90-228-1864-0}}
* {{cite book |editor-last=Raven |editor-first=G.J.A. |date=1988 |title=De kroon op het anker: 175 jaar Koninklijke Marine |language=Dutch|edition= |url= |location=Amsterdam |publisher=De Bataafsche Leeuw |page= |isbn=90-6707-200-1}}

{{T class submarine}}
{{WWII British ships}}
{{Authority control}}

{{DEFAULTSORT:British T Class Submarine}}
[[Category:Submarine classes of the British Royal Navy|T class]]
[[Category:British T-class submarines| ]]