View source for Dunkerque-class battleship

{{Short description|Ship class in the French-navy}}
{{Use shortened footnotes|date=December 2022}}
{{good article}}
{| {{Infobox ship begin}}
{{Infobox ship image
| Ship image   = Dunkerque-1.jpg
| Ship caption = ''Dunkerque''
}}
{{Infobox ship class overview
| Name = ''Dunkerque'' class
| Builders = 
*[[Arsenal de Brest]]
*[[Ateliers et Chantiers de Saint-Nazaire Penhoët|A C de Saint-Nazaire Penhoët]] 
| Operators = {{navy|France}}
| Class before =
* {{sclass|Lyon|battleship|4}} (planned)
* {{sclass|Bretagne|battleship|4}} (actual)
| Class after = {{sclass|Richelieu|battleship|4}}
| Built range = 1932–1938
| In service range = 1937–1942
| Total ships completed=2
| Total ships lost= 2
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=<ref>Figures are for ''Dunkerque''</ref>
|Ship type=[[Fast battleship]]
|Ship displacement=
*{{convert|26500|MT|LT|abbr=on|lk=on}} ([[Displacement (ship)#Standard displacement|standard]])
*{{convert|35500|MT|LT|abbr=on}} ([[deep load]])
|Ship length={{cvt|214.5|m|ftin}}
|Ship beam={{cvt|31.1|m|0}}
|Ship draft={{cvt|8.7|m|ftin}}
|Ship power=
*{{convert|107500|shp|lk=on|abbr=on}}
*6 [[:fr:Fonderie d'Indret|Indret]] [[boiler]]s
|Ship propulsion=
*4 × [[propeller|screws]]
*4 × geared [[steam turbine]]s
|Ship speed={{convert|29.5|kn|lk=in}}
|Ship range=
*{{convert|7,850|nmi|lk=in|abbr=on}} at {{convert|15|kn}}
*{{convert|2,450|nmi|abbr=on}} at {{convert|28.5|kn}}
|Ship crew=
*81&nbsp;officers
*1,300&nbsp;enlisted men
|Ship armament=
*8 ×  [[330mm/50 Modèle 1931 gun|{{convert|330|mm|abbr=on}} gun]]s
*16 × [[Canon de 130 mm Modèle 1932 and 1935|{{convert|130|mm|abbr=on|1}}]] [[Dual-purpose gun|DP guns]]
*8 × [[Canon de 37 mm Modèle 1925|{{convert|37|mm|in|abbr=on}}]] [[AA gun]]s
*32 × [[Hotchkiss M1929 machine gun|{{convert|13.2|mm|in|abbr=on}}]] [[anti-aircraft machinegun|AA machineguns]]
|Ship armour=
*[[Belt armour]]: {{convert|225|mm|abbr=on}}
*[[Deck (ship)|Main deck]]: {{convert|115|mm|abbr=on}}
*[[Gun turret]]s: {{convert|330|mm|abbr=on}}
*[[Conning tower]]: {{convert|270|mm|abbr=on|1}}
|Ship aircraft=2 [[floatplane]]s
|Ship aircraft facilities=
|Ship notes= 
}}
|}

The '''''Dunkerque'' class''' was a pair of [[fast battleship]]s built for the [[French Navy]] in the 1930s; the two ships were {{ship|French battleship|Dunkerque||2}} and {{ship|French battleship|Strasbourg||2}}. They were the first French battleships built since the {{sclass|Bretagne|battleship|4}} of pre-[[World War I]] vintage, and they were heavily influenced by the [[Washington Naval Treaty|Washington Treaty system]] that limited naval construction in the 1920s and 1930s. French battleship studies initially focused on countering fast Italian [[heavy cruiser]]s, leading to early designs for small, relatively lightly protected [[capital ship]]s. But the advent of the powerful German {{sclass|Deutschland|cruiser|1}}s proved to be more threatening to French interests, prompting the need for larger and more heavily armed and armoured vessels. The final design, completed by 1932, produced a small battleship armed with eight {{cvt|330|mm}} guns that were concentrated in two quadruple [[gun turret]]s forward, with armour sufficient to defeat the ''Deutschland''s{{'}} {{cvt|283|mm}} guns. ''Strasbourg'' was completed to a slightly modified design, receiving somewhat heavier armour in response to new Italian {{sclass|Littorio|battleship|1}}s. Smaller and less heavily armed and armoured than all other [[treaty battleship]]s, the ''Dunkerque''s have sometimes been referred to as [[battlecruiser]]s.

The two ships had relatively short careers; completed just before the outbreak of [[World War II]], they served briefly with the Atlantic Squadron in the late 1930s, and ''Dunkerque'' made several visits abroad, including to [[French West Africa]] in 1938 and visits to Britain in 1937 and 1939. With war looming in August 1939, the French created the ''[[Force de Raid]]'' (Raiding Force), centred on the two ''Dunkerque''s, which was tasked with hunting down the ''Deutschland''s that were expected to operate in the Atlantic as [[commerce raider]]s. The French never caught the German cruisers, and instead the vessels were sent to [[Mers-el-Kébir]] to deter Italy from entering the war against France. After Germany defeated France in the [[Battle of France]] in June 1940, the French were forced to neutralise their fleet, and the two ''Dunkerque''s were to remain inactive at Mers-el-Kébir. Unaware that Germany had no intention of seizing the ships, the British sent [[Force H]] to sink the ships; ''Dunkerque'' was damaged in the [[Attack on Mers-el-Kébir]] in July, but ''Strasbourg'' escaped to [[Toulon]], where she became the [[flagship]] of the ''[[Forces de haute mer]]'' (High Seas Forces).

''Dunkerque'' was badly damaged in another attack but was temporarily repaired and eventually returned to Toulon for permanent repairs. ''Strasbourg'' saw little activity during this period, as the armistice with Germany limited training operations. ''Dunkerque'' was still in [[drydock]] when the Germans launched [[Case Anton]], occupying the rest of France in November 1942. To prevent the Germans from seizing the ships, the French Navy [[Scuttling of the French fleet at Toulon|scuttled the fleet in Toulon]]. Both ships were badly damaged and were handed over to Italian control, where they were partially [[ship breaking|broken up]]. Their hulks, which were bombed by American aircraft in 1944, were eventually sold for scrap in the 1950s.

== Background and development ==
[[File:Italian cruiser Trieste NH 86004.jpg|thumb|left|{{ship|Italian cruiser|Trieste||2}}, one of the {{sclass|Trento|cruiser|1}}s the early French battleship designs were intended to counter]]
Wary of another [[naval arms race]] similar to the [[Anglo-German naval arms race|Anglo-German race]] that was seen as [[Causes of World War I|contributing to the start]] of [[World War I]], the world's major navies held the [[Washington Naval Conference]] in 1921 to discuss controls on [[battleship]] construction, both to limit their size and armament but also to limit the number of ships that could be built. The resulting Washington Naval Treaty limited the [[French Navy]] to {{convert|175000|LT|t|lk=on}} of total battleship tonnage; French resistance to a halt on battleship construction, in light of the obsolescent {{sclass|Courbet|battleship|5}} and ''Bretagne''-class battleships that formed the core of its fleet, led to an exception for France (and Italy) to replace {{convert|70000|LT|t}} worth of battleships during the moratorium, to be laid down in 1927 and 1929. Maximum displacement of any new battleship was restricted to {{convert|35000|LT|t}} at [[standard displacement]].{{sfn|Jordan & Dumas|pp=15–18}}{{sfn|Labayle-Couhat|pp=37–38}}

In 1926, the Chief of the Naval General Staff, Admiral [[Henri Salaun (French Navy officer)|Henri Salaun]], requested a new capital ship design with a [[displacement (ship)|displacement]] of {{convert|17500|LT|t}}, intended to counter the new generation of Italian heavy cruisers. The first of these Italian vessels, the two {{sclass|Trento|cruiser|1}}s, were fast and posed a considerable threat to French shipping in the western Mediterranean between metropolitan France and its colonies in [[French North Africa]]. The new French vessel would be armed with a [[Artillery battery#Naval usage|battery]] of eight {{cvt|305|mm|0}} guns mounted in two quadruple [[gun turret]]s, both arranged forward, since the French envisioned using the ships to chase down the Italian cruisers. The ships would have been armoured to resist the {{cvt|203|mm|0}} guns of the Italian cruisers, and since the guns were concentrated forward, the amount of armour necessary to protect the ship's vitals allowed significant savings in weight. For the prescribed displacement, four such vessels could be built in the allotted 70,000&nbsp;tons. The concept was strongly influenced by the British {{sclass|Nelson|battleship|1}}s, which mounted their battery entirely forward to save armour weight.{{sfn|Jordan & Dumas|pp=19–21, 32}}

[[File:Dunkerque class battleships 37 000 project 33 knot.svg|thumb|left|Illustration of the 36,000-ton design]]

The German {{sclass|Deutschland|cruiser|1}}s, which were armed with a battery of six 283&nbsp;mm guns, coupled with hesitance on the French Navy's part to commit to small capital ships while Italy still kept its allotted tonnage uncommitted led the French to abandon the 17,500-ton project. New design studies were prepared in 1926–1927, resulting in several proposals in 1928 for a {{convert|37000|t|LT|order=flip|adj=on}} design. These ships were in most respects an enlarged version of the {{sclass|Suffren|cruiser|4}} of heavy cruisers then being built. The increase in displacement brought with it a third quadruple 305&nbsp;mm turret placed aft and heavier armour protection in a version capable of {{convert|33|kn|lk=in}}, while a slower {{convert|27|kn|adj=on}} ship was to be armed with six {{cvt|406|mm|0}} guns in twin turrets. Shortages of funding, both for the ships themselves and the necessary improvements to shipyards and harbour facilities to build and operate the vessels ended the proposals. Additionally, political concerns, particularly French efforts to lead disarmament talks in the [[League of Nations]], convinced the French government to delay the construction of any new battleships.{{sfn|Jordan & Dumas|pp=22–27}}

[[File:German cruiser Deutschland in 1935.jpg|thumb|The German cruiser {{ship|German cruiser|Deutschland||2}}, which prompted significant revisions to what eventually became the ''Dunkerque'' class]]

Design studies continued after the [[London Naval Treaty]], where the British had unsuccessfully pushed for reductions in the maximum displacement and gun calibre. As a show of support for the British position, the French naval command requested designs with a maximum displacement of {{cvt|25000|LT|t}}—the ceiling sought by the British—and a minimum {{cvt|23333|LT|t}}—the maximum displacement that would allow three new ships to be built using the allotted 70,000 tons that France still had available. Apart from the increased size and thicker [[belt armour]], the proposed ship carried the same main battery as the 17,500-ton ship. By this time, Germany had finally begun building the first of the ''Deutschland''s; this led to renewed concerns over the level of armour protection, which was still too thin to defeat the German 283&nbsp;mm gun. After pressure from the French parliament over the perceived weakness of the design, the [[Chief of Staff of the French Navy|Chief of the Naval Staff]] issued a new set of requirements, including an increase in standard displacement to {{cvt|25000|LT|t}}, an armament of eight 330&nbsp;mm guns, and armour sufficient to resist 283&nbsp;mm projectiles.{{sfn|Jordan & Dumas|pp=28–29}}

As refining work on the design progressed, it became apparent that the 25,000-ton standard displacement was too low to accommodate the requested characteristics, so it was increased first to {{cvt|26000|LT|t}} and finally to {{cvt|26500|LT|t}}. Work on the project was completed by early 1932 and it was formally approved on 27 April. The improved armour layout not only rendered the ships immune to 283&nbsp;mm fire at expected battle ranges, but it was also capable of defeating the 305&nbsp;mm guns of the older Italian battleships still in service. The first ship, to be named ''Dunkerque'', was ordered on 26 October 1932, with a second projected for the 1934 programme. The Italian announcement in May 1934 that they would begin building new 35,000-ton battleships armed with {{cvt|381|mm|0}} guns threatened to throw French plans into disarray, since these ships would be vastly superior to the ''Dunkerque'' design, but the first French ship had already been [[keel laying|laid down]] and it was too late to redesign the second vessel, ''Strasbourg'', in response. Side armour for the second ship would be slightly increased while design work began immediately on a 35,000-ton counter to the Italian ships, which produced the {{sclass|Richelieu|battleship|4}}.{{sfn|Jordan & Dumas|pp=29–31}}

The ''Dunkerque''-class ships' relatively small size and light armament and emphasis on speed rather than protection, especially compared to the other [[treaty battleship]]s of the period, has led some to classify them as battlecruisers.{{sfn|Gardiner|p=27}}

== Characteristics ==
[[File:Dunkerque class battleships inboard profile EN.svg|upright=2.5|thumb|Inboard profile of ''Dunkerque'']]

The two ships differed slightly in their dimensions; both were {{cvt|209|m|ftin}} [[length between perpendiculars|long between perpendiculars]], while ''Dunkerque'' was {{cvt|215.14|m|ftin}} [[length overall|long overall]] while ''Strasbourg'' was {{cvt|215.5|m|0}} overall. The two ships both had a [[beam (nautical)|beam]] of {{cvt|31.1|m|0}}. ''Dunkerque'' displaced {{convert|26500|LT|t}} standard, {{cvt|30750|t|LT|order=flip}} normally, and {{convert|35500|t|LT|order=flip}} [[Full-load displacement|fully loaded]]. ''Strasbourg'' was slightly heavier, at {{cvt|27300|LT|t}} standard, {{cvt|31570|t|LT|order=flip}} normally, and {{cvt|36380|t|LT|order=flip}} at full load, with the difference being the result of increased armour protection. [[Draft (hull)|Draft]] for ''Dunkerque'' measured {{cvt|8.57|m|ftin}} normally and increased to {{cvt|9.71|m|ftin}} at full load, and ''Strasbourg'' drew {{cvt|8.73|m|ftin}} at normal loading and {{cvt|9.89|m|ftin}} at full load.{{sfn|Jordan & Dumas|p=38}}

''Dunkerque'' had a crew of 81&nbsp;officers and 1,300&nbsp;sailors, while ''Strasbourg''{{'}}s crew consisted of 32&nbsp;officers and 1,270&nbsp;sailors, the additional crew aboard ''Dunkerque'' being an admiral's staff, as she typically operated as a [[flagship]]. Each vessel carried a number of smaller boats, including a variety of motor [[Pinnace (ship's boat)|pinnaces]], [[whaleboat]]s, [[Launch (boat)|launches]], and [[dinghy|dinghies]]. Steering was controlled by a single [[rudder]]; the rudder had a range of train from 0 to 32&nbsp;degrees from the centreline, but had a tendency to jam when turned further than 25&nbsp;degrees. The rudder was electrically operated, but the ships also had manual controls in the event of a power failure.{{sfn|Jordan & Dumas|pp=38, 50, 56}}

The ships carried three [[Loire 130]] [[seaplane]]s for use as [[reconnaissance aircraft|reconnaissance]] and spotter aircraft on the [[fantail (ship)|fantail]], and the aircraft facilities consisted of a {{cvt|22|m|ftin}} steam [[aircraft catapult|catapult]], a [[aircraft hangar|hangar]], and a crane to handle the floatplanes. The hangar had two [[storey]]s and an internal elevator and included workshops to maintain the aircraft while underway. The crane could be folded flat across the deck while not in use.{{sfn|Roberts|p=259}}{{sfn|Jordan & Dumas|pp=38, 51–53}}

===Machinery===
[[File:Dunkerque class battleships power plant.en.svg|thumb|upright=2.5|Arrangement of the ships' propulsion systems]]
The ships were powered by four sets of [[Parsons Marine Steam Turbine Company|Parsons]] geared [[steam turbines]] driving four 3-bladed [[propeller|screws]] for ''Dunkerque'' and 4-bladed screws for ''Strasbourg''. Steam was provided by six oil-fired {{Interlanguage link|Indret|fr|Fonderie d'Indret}} [[water-tube boiler]]s, ducted into a single large [[funnel (ship)|funnel]]. The ''Dunkerque''s adopted the [[unit system of machinery]] for their propulsion system, which split the machinery into two separate systems. The arrangement offered improved damage resistance, since one system could be disabled due to battle damage and the other could remain in operation. The ships' boilers were arranged in side-by-side pairs in three [[fire room|boiler rooms]]; the first was placed below the command tower and the other two were placed below the funnel. The turbines were divided between two [[engine room]]s; the first contained the outer shafts and was placed between the boiler rooms, and the inner turbines were placed in an engine room aft of the rear boiler room.{{sfn|Jordan & Dumas|pp=49–50}}

The ships were rated for a top speed of {{convert|29.5|kn}} from {{convert|107000|shp|lk=on}} as designed. On speed tests, ''Dunkerque'' reached a maximum of {{convert|31.06|kn}} from {{cvt|135585|shp}}, while ''Strasbourg'' made {{convert|30.9|kn}} from {{cvt|131960|shp}}. [[Fuel oil]] storage amounted to {{cvt|4500|to|5000|t|LT|order=flip}} in peacetime but it was reduced to {{cvt|3700|t|LT|order=flip}} in wartime to prevent the weight of fuel from reducing the armoured [[freeboard (nautical)|freeboard]]. At a cruising speed of {{convert|15|kn}} under wartime fuel conditions, the ships had a range of {{convert|7850|nmi|lk=in}}, and at {{convert|28|kn}}, their cruising radius fell to {{cvt|2450|nmi}}. The ships' electrical systems were powered by four {{cvt|900|kW}} [[turbo generator]]s, with two per engine room, with backup power for critical systems provided by two {{cvt|100|kW}} [[diesel generator]]s located below the tower. For use while in port, three {{cvt|400|kW}} diesel generators were fitted, and these were located in a separate room below the ammunition [[magazine (artillery)|magazines]] for the main battery.{{sfn|Jordan & Dumas|pp=38, 49–51}}

===Armament===
Both ships were armed with eight [[330mm/50 Modèle 1931 gun|330&nbsp;mm]] 50-[[caliber (artillery)|caliber (cal.)]] guns arranged in two quadruple gun turrets, both of which were placed in a [[superfire|superfiring pair]] forward of the superstructure.{{sfn|Roberts|p=259}} [[Compagnie des forges et aciéries de la marine et d'Homécourt|Saint Chamond]] designed the turrets, which allowed for a maximum elevation to 35&nbsp;degrees for a maximum range of {{cvt|41500|m|yd}} and depression to -5&nbsp;degrees. The guns were carried in individual cradles that allowed for limited independent operation, and the guns could be loaded at any angle, though the crews typically returned them to 15&nbsp;degrees to reduce the likelihood of the shells becoming jammed, a problem that could occur when the guns were at high angles of elevation and other guns in the same turret were fired. To reduce the risk of a single shell hit disabling all four guns, the turrets were divided by an internal [[bulkhead (partition)|bulkhead]], and they were spaced {{cvt|27|m|ftin}} apart. The guns fired a {{cvt|570|kg}} shell at a [[muzzle velocity]] of {{cvt|870|m/s}}; the shells featured a relatively large bursting charge for their size, reflective of the fact that the ''Dunkerque''s were intended to fight the relatively lightly-armoured ''Deutschland''s. Ammunition storage amounted to 456&nbsp;shells for the forward turret and 440&nbsp;shells for the superfiring turret. Their [[rate of fire]] was between 1.5 and 2 shots per gun per minute.{{sfn|Jordan & Dumas|pp=33–38}}

The ships' secondary armament consisted of sixteen [[Canon de 130 mm Modèle 1932 and 1935|{{convert|130|mm|abbr=on}} 45-cal.]] [[dual-purpose gun]]s; these were mounted in three quadruple and two twin turrets. The quadruple turrets were placed on the stern, with one on the centreline on the superstructure and the other two on either side on the upper [[deck (ship)|deck]], and the twin turrets were located [[amidships]], just forward of the funnel.{{sfn|Roberts|p=259}} They were the first dual-purpose guns of the French Navy. The guns had range of elevation from -10 to 75&nbsp;degrees; at 45&nbsp;degrees, their maximum range was {{cvt|20800|m|yd}}. Their rate of fire was 10 to 12&nbsp;shells per minute. They were supplied with both {{cvt|33.4|kg}} armour-piercing (AP) shells for use against warships and {{cvt|29.5|kg}} high-explosive (HE) shells for use against aircraft. Each gun was allocated approximately 400&nbsp;shells, a third of which were the AP shells, with the remainder being HE and [[star shell]]s.{{sfn|Jordan & Dumas|pp=37–38}}

Close-range antiaircraft defence was provided by a battery of ten [[Canon de 37 mm Modèle 1925|{{convert|37|mm|in|abbr=on}}]] guns in twin mounts for ''Dunkerque'' and eight such guns for ''Strasbourg'', along with thirty-two [[Hotchkiss M1929 machine gun|{{convert|13.2|mm|in|abbr=on}}]] machine guns in quadruple mounts for ''Dunkerque'' and thirty-six guns for ''Strasbourg''. Two of the 37&nbsp;mm mounts were placed abreast of the superfiring turret, with the remaining three on the aft superstructure one of which was on the centreline; ''Strasbourg'' omitted the centreline mount, receiving instead another quadruple 13.2&nbsp;mm gun in its place. Two of the 13.2&nbsp;mm mounts were located on the upper deck on either side of the command tower, four were arranged around the upper deck further aft, and the remaining two were placed on the aft superstructure.{{sfn|Jordan & Dumas|pp=41–38}}

====Fire control====
The ships were the first French battleships designed with [[Fire-control system|fire-control directors]]. The ships carried five directors that each had a stereoscopic [[Rangefinding telemeter|rangefinder]] for the main and secondary batteries. For the main guns, one director with a {{cvt|12|m|abbr=on|ftin}} rangefinder was mounted on the tower and a second with an {{cvt|8|m|ftin}} rangefinder on the aft superstructure. Atop the forward director were a pair of directors for the secondary guns, the first with a {{cvt|6|m|ftin}} rangefinder and the top unit with a {{cvt|5|m|ftin}} rangefinder. A third director for the secondary battery was mounted on the roof of the aft main director, also with a 6&nbsp;m rangefinder. Both main-battery turrets were fitted with their own 12&nbsp;m rangefinders and the secondary quadruple turrets received 6&nbsp;m rangefinders for local control in the event the directors were disabled. Fire control equipment for the anti-aircraft battery consisted of four {{cvt|1|m|ftin}} rangefinders, two forward on the tower and two on the aft superstructure. The directors were used to gather range, bearing, and inclination data, which was then sent to a central control station below the armour decks; there, plotting tables and [[analog computer]]s were used to calculate firing solutions for the guns. The guns were remotely controlled via electric motors, but the system proved to be problematic in service, as the training and elevation gears were unreliable, the system that communicated commands from the directors to the guns frequently did not work, and the gunners needed to revert to manual control to make small adjustments. The ships' systems were modified in an attempt to correct these problems, but they never worked reliably.{{sfn|Jordan & Dumas|pp=38–40}}

===Armour===
[[File:French battleship Dunkerque armour protection-EN.svg|upright=2.5|thumb|Armour layout ''Dunkerque'']]

The ships' protection scheme incorporated the [[All or nothing (armor)|all or nothing]] principle. Their belt armour was {{convert|225|mm|abbr=on}} thick amidships for ''Dunkerque'' and {{cvt|283|mm}} for ''Strasbourg'', backed by {{cvt|60|mm}} of [[teak]] for both ships, extending from the forward 330&nbsp;mm magazine to the aft 130&nbsp;mm magazine. The belt was capped on either end by transverse armoured bulkheads; the forward bulkheads were {{cvt|210|mm}} for ''Dunkerque'' and {{cvt|228|mm|0}} for ''Strasbourg'', and the aft bulkheads were {{cvt|180|mm}} and 210&nbsp;mm, respectively. It was inclined 11.3&nbsp;degrees from the vertical to improve its resistance to [[plunging fire]]. The belt extended from about {{cvt|3.5|m|ftin}} above the [[waterline]] and {{cvt|2|m}} below. The armoured box created by the belt and bulkheads was covered by two armour decks, the first of these connected to the top of the belt and was {{cvt|125|mm}} over the forward magazines and reduced to {{cvt|115|mm}} over the propulsion machinery and aft magazines, backed by a {{cvt|15|mm}} steel deck. The lower deck was {{cvt|40|mm}} thick, with sloping sides that connected to the lower edge of the belt; for ''Strasbourg'', the sloped sides were increased to {{cvt|50|mm|0}}. Aft of the [[Armored citadel|central citadel]], the stern was protected by a {{cvt|100|mm}} deck with sloped sides, and additional 50&nbsp;mm plates covered that portion of the deck that protected the steering gear.{{sfn|Garzke & Dulin|pp=71–72}}{{sfn|Jordan & Dumas|pp=42–44}}

The main-battery turrets were protected by 330&nbsp;mm of armour plate on the faces, {{cvt|250|mm}} on the sides, and {{cvt|150|mm}} on the roofs, while ''Strasbourg'' received slightly better protection, with {{cvt|360|mm|1}} faces and {{cvt|160|mm}} roofs. Their rear plates varied between the turrets and between the ships, and were heavy to balance the weight of the guns. For ''Dunkerque'', her forward turret had a {{cvt|345|mm}} rear plate and her superfiring turret had a {{cvt|335|mm}} rear; ''Strasbourg'' had {{cvt|352|mm}} and {{cvt|342|mm}} plates, respectively. The turrets sat atop armoured [[barbette]]s that were {{cvt|310|mm}} for ''Dunkerque'' and {{cvt|340|mm|1}} for ''Strasbourg''; both were reduced to 50&nbsp;mm below the upper deck. Both ships' secondary turrets had {{cvt|135|mm}} faces, {{cvt|90|mm}} sides and roofs, and {{cvt|80|mm}} rears, atop {{cvt|120|mm}} barbettes. The [[conning tower]] had {{cvt|270|mm|1}} thick sides, reduced to {{cvt|220|mm}} on its rear and {{cvt|130|to|150|mm}} on the roof. The tower received light protection against aircraft [[strafing]] attacks in the form of {{cvt|10|mm}} plating, while the fire-control directors were protected with {{cvt|20|mm}} steel.{{sfn|Garzke & Dulin|pp=71–72}}{{sfn|Jordan & Dumas|pp=44–47}}

Defence against underwater attacks—[[torpedo]]es and [[naval mine]]s—came in the form of layered [[torpedo bulkhead]]s that incorporated liquid-filled voids to absorb blast effects. In addition, a [[rubber]]-based compound referred to as ''ébonite mousse'' was used to help absorb the impact and control flooding in critical areas. The underwater protection system covered the same area of the hull as the belt armour. The system included three bulkheads, the first of which was {{cvt|16|mm}} thick, followed by a 10&nbsp;mm bulkhead, and backed by the main torpedo bulkhead, which was {{cvt|30|mm}} thick. Where it protected the machinery spaces, the system had a depth of almost {{cvt|7.5|m|ftin}}, compared to the depth of contemporary foreign ships, which was typically around {{cvt|5|m|ftin}}. Where the system had to be narrowed, abreast the forward and aft magazines, the main bulkhead increased in thickness to 40 and then 50&nbsp;mm to account for the reduction in effectiveness. To prevent the explosion of a mine below the hull from breaching the ammunition magazines, the bottoms of the magazines were raised above the double bottom, and they were protected by 30&nbsp;mm plates.{{sfn|Jordan & Dumas|pp=48–49}}

===Modifications===
The ships received relatively minor modifications in their short careers; both ships received a [[funnel cap]] to reduce smoke interference with the command tower in 1938. After the start of [[World War II]], the 12&nbsp;m rangefinder for the forward main battery director was replaced with a {{cvt|14|m|ftin}} version aboard ''Dunkerque'', while ''Strasbourg'' did not receive an updated rangefinder. A [[degaussing]] cable was fitted to ''Strasbourg'' to reduce the risk of detonating German magnetic mines during a refit from November 1939 to January 1940, and during another refit in August–September, a steel screen was erected to protect the light anti-aircraft guns from strafing attacks. ''Strasbourg'' had her command tower modified in November and December 1940 to refit her for use as a flagship, as ''Dunkerque'' had been disabled by that point. While ''Dunkerque'' was under repair at [[Toulon]] in 1942, consideration was given to replacing her aviation facilities with additional 37&nbsp;mm guns to improve her anti-aircraft defences, but this work was not begun before the [[Scuttling of the French fleet at Toulon|fleet was scuttled in November]]. During another refit from January to April 1942, ''Strasbourg''{{'}}s forward 37&nbsp;mm mounts were moved from her [[forecastle]] to the weather deck, as they were on ''Dunkerque'', and she received an [[Early-warning radar|air-search radar]] set with four antennae. Early tests with the set indicated a detection range of {{cvt|50|km}}.{{sfn|Jordan & Dumas|pp=54–57}}

== Ships==
{|class="wikitable plainrowheaders"
|+ Construction data
! scope="col" | Ship
! scope="col" | Builder {{sfn|Jordan & Dumas|p=59}}
! scope="col" | Programme {{sfn|Jordan & Dumas|p=59}}
! scope="col" | [[keel laying|Laid down]] {{sfn|Jordan & Dumas|p=59}}
! scope="col" | [[ceremonial ship launching|launched]] {{sfn|Jordan & Dumas|p=59}}
! scope="col" | [[ship commissioning|Commissioned]] {{sfn|Jordan & Dumas|p=59}}
! scope="col" | In service {{sfn|Jordan & Dumas|p=59}}
|-
! scope="row" | [[French battleship Dunkerque|''Dunkerque'']]
|[[Brest Arsenal|Arsenal de Brest]]
|1931
|24 December 1932
|2 October 1935
|31 December 1936
|1 September 1938
|-
! scope="row" | [[French battleship Strasbourg|''Strasbourg'']]
|[[Ateliers et Chantiers de Saint-Nazaire Penhoët]], [[Saint-Nazaire]]
|1934
|24 November 1934
|12 December 1936
|15 September 1938
|24 April 1939
|}

== Service history ==
[[File:Dunkerque1940.png|thumb|left|''Dunkerque'' as she appeared in 1940]]

After commissioning in 1936, ''Dunkerque'' required extensive testing and evaluation, including extensive trials with her guns, as both the main and secondary battery mounts were new to French naval service. During this period, in May 1937, she represented France at the [[Fleet review (Commonwealth realms)|Naval Review]] for the [[coronation of King George VI and Queen Elizabeth]]. In early 1938, ''Dunkerque'' toured France's [[West Africa]]n colonies and islands in the Caribbean. After finally being pronounced ready for active service in September, she became the flagship of the Atlantic Squadron. Shortly thereafter, ''Strasbourg'' was commissioned to begin working up, but the increasingly unstable international situation in Europe forced the French to rush the ship through trials; ''Strasbourg'' got little more than six months of testing and training before entering service, compared to more than two years for ''Dunkerque''.{{sfn|Dumas|p=65}}{{sfn|Jordan & Dumas|pp=58–61}}

During the [[Sudetenland Crisis]] with Germany in early April 1939, ''Dunkerque'' was sent to cover the return of the [[training ship|training cruiser]] {{ship|French cruiser|Jeanne d'Arc|1930|2}} as it returned from a cruise in the Caribbean, as a nearby German squadron would have threatened the vessel if war had broken out. ''Strasbourg'' then joined the squadron and the two ships were designated the 1st Battle Division. The ships visited Portugal in May before embarking on a lengthy tour of Britain later that month and in June. Both vessels conducted extensive training exercises off [[Brittany]] in July and August as Europe drifted toward war. As tensions rose with Germany over the latter's aggressive demands on Polish territory, the British and French naval commands agreed to divide responsibilities for joint operations in the anticipated war; France would cover [[Allies of World War II|Allied]] shipping in the central Atlantic, and for this purpose, ''Dunkerque'' and ''Strasbourg'' were assigned to the new ''[[Force de Raid]]'' (Raiding Force) to hunt down German [[commerce raider]]s.{{sfn|Jordan & Dumas|pp=65–66}}{{sfn|Dumas|pp=67–68}}

===World War II===
[[File:Strasbourg1942.png|thumb|left|''Strasbourg'' as she appeared in 1942]]

With the outbreak of war in early September, the ''Force de Raid'', under the command of [[Squadron vice-admiral|''Vice-amiral d'Escadre'']] (Squadron Vice Admiral) [[Marcel-Bruno Gensoul]], went to sea when reports indicated that the German ''Deutschland''-class cruisers had sortied to attack Allied shipping. The German raiders were still in the [[North Sea]], however, and so after meeting a French [[passenger liner]], the ''Force de Raid'' returned to port. The unit was then split to increase the chances of finding the German cruisers, with ''Dunkerque'' operating out of [[Brest, France]], with the [[aircraft carrier]] {{ship|French aircraft carrier|Béarn||2}} while ''Strasbourg'' moved south to [[Dakar]] in [[French West Africa]] in company with the British carrier {{HMS|Hermes|95|6}}. In November, ''Dunkerque'' joined the [[battlecruiser]] {{HMS|Hood}} to hunt for the German battleships {{ship|German battleship|Scharnhorst||2}} and {{ship|German battleship|Gneisenau||2}}, but they were unable to locate the German vessels.{{sfn|Rohwer|pp=2, 6, 9}}{{sfn|Jordan & Dumas|pp=68–69}}

In late November, ''Strasbourg'' was recalled from Dakar and the ''Force de Raid'' was reconstituted. ''Dunkerque'' carried a shipment of part of the [[Banque de France]]'s gold reserve to Canada and then escorted a [[troop ship]] convoy to Britain in December. The ships were sent to the Mediterranean in early 1940 as the threat of war with Italy increased; the French hoped to use the [[show of force]] to deter Italy from entering the war. Consideration was given to sending them to support the [[Norwegian Campaign]] in April 1940, but Italy's increasingly hostile posture forced the French to keep them in the Mediterranean. Based in [[Mers-el-Kébir]] along with other elements of the French fleet, the ships saw little activity during the [[Battle of France]] that ended with French defeat; the [[Second Armistice at Compiègne|Armistice]] mandated that the French fleet would be demilitarised, with ''Dunkerque'' and ''Strasbourg'' to remain in Mers-el-Kébir.{{sfn|Jordan & Dumas|pp=69–70}}

====Mers-el-Kébir====
[[File:Croiseur de bataille Strasbourg 03-07-1940.jpg|thumb|''Strasbourg'' slips her moorings and makes for open water while under fire from the British [[Force H]]]]
{{main|Attack on Mers-el-Kébir}}

The British government, incorrectly fearing that the Germans intended to seize the French fleet and employ it against Britain, embarked on a campaign to neutralise the vessels. The British [[Force H]], which included ''Hood'' and the battleships {{HMS|Resolution|09|2}} and {{HMS|Valiant|1914|2}}, was sent to either compel the French vessels at Mers-el-Kébir to join the [[Free French Forces]], be demilitarised in France's Caribbean colonies or the United States, or to sink them. After Gensoul rejected their demands, the British opened fire. The French ships were moored with their sterns toward the sea, which initially prevented ''Dunkerque'' and ''Strasbourg'' from returning fire until they could get underway. The {{cvt|15|in|0}} guns of the British ships quickly inflicted serious damage on ''Dunkerque'' and the old battleships {{ship|French battleship|Bretagne||2}} and {{ship|French battleship|Provence||2}}. ''Dunkerque''{{'}}s crew was forced to beach her to prevent her from sinking; ''Bretagne'' exploded and ''Provence'' sank to the harbour bottom. ''Strasbourg'', however, was able to slip her moorings and escape from the harbour in the confusion. Escorted by four destroyers, she avoided the British fleet and escaped to Toulon.{{sfn|Rohwer|p=31}}{{sfn|Jordan & Dumas|pp=75, 77, 82–83}}

Repair work began almost immediately on ''Dunkerque'', with a view toward restoring the ship to seaworthy condition so she could be returned to Toulon for [[drydock]]ing and permanent repairs. Upon learning that the ship had not been permanently disabled, the British returned and launched an air strike from the carrier {{HMS|Ark Royal|91|6}}, for which Gensoul and ''Dunkerque''{{'}}s commanders had failed to erect defences, either in the form of [[torpedo net]]s or manned anti-aircraft guns. The [[Fairey Swordfish]] [[torpedo bomber]]s failed to score any direct hits on ''Dunkerque'', but a pair of torpedoes struck the patrol boat ''Terre-Neuve'' that had been moored alongside the ship. Those hits led to a secondary explosion of that vessel's [[depth charge]]s that amounted to an equivalent of eight aerial torpedoes, which caused extensive damage to ''Dunkerque''{{'}}s hull. Nevertheless, repair work quickly resumed, and her holed hull was plated over and pumped dry.{{sfn|Jordan & Dumas|pp=84–86, 88}}{{sfn|Rohwer|pp=31–32}}

In the meantime, ''Strasbourg'' became the flagship of the ''[[Forces de haute mer]]'', which was created from the remains of the French fleet still available in Toulon, under the command of ''[[Amiral]]'' [[Jean de Laborde]]. During this period, limitations on French naval activity from the armistice kept ''Strasbourg'' largely in port, limited to two training cruises per month. In September 1940, the ship and several cruisers sortied to cover ''Provence'', which had been repaired and refloated after the attack on Mers-el-Kébir, as she returned to Toulon.{{sfn|Jordan & Dumas|pp=88–91}}

By April 1941, ''Dunkerque'' was back in a seaworthy condition, though tests of her propulsion system were necessary before she would be able to get underway. Heavy fighting between British and Italian forces during the [[Battle of the Mediterranean|Mediterranean Campaign]] delayed ''Dunkerque''{{'}}s return to France until February 1942. Escorted by five destroyers and some 65&nbsp;aircraft, she arrived in Toulon on 20 February and was later drydocked there in June to begin repairs.{{sfn|Jordan & Dumas|pp=88–89}}

====Scuttling at Toulon====
[[File:Battleship Strasbourg after bomb attack, 1944.jpg|thumb|''Strasbourg'' after having been bombed by US Air Force bombers on 18 August 1944]]
{{main|Scuttling of the French fleet at Toulon}}

Following [[Operation Torch]], the Allied invasion of French North Africa on 8 November, Germany launched [[Case Anton]] in retaliation, moving to seize all of the so-called "[[Zone libre]]", the part of Vichy France that had up to that point remained unoccupied. Expecting the Germans to arrive to commandeer the ships, de Laborde ordered his crews to prepare to [[scuttling|scuttle]] their ships. When the Germans arrived in Toulon on 27 November, the work had been completed and de Laborde issued the order. Sabotage teams went through the ships, destroying any equipment that might be usable by the Germans, including rangefinders, [[gyrocompass]]es, and radios. They lit fires in the boilers and shut off the water supply so that the boilers would overheat and explode, and they packed gun barrels with explosives. ''Strasbourg''{{'}}s crew then opened the [[seacock]]s and detonated scuttling charges to ensure the ship sank. ''Dunkerque'' was at that time still incomplete in the drydock, so she was set on fire, damaged by demolition charges, and then flooded in the drydock when the [[Lock (water navigation)|locks]] were opened.{{sfn|Jordan & Dumas|pp=92–92}}

Italy received control over most of the wrecks, as Germany had little interest; the Italian fleet sought as many vessels as possible, but ''Dunkerque'' and ''Strasbourg'' were too badly damaged to be repaired quickly, and so they wrote them off as a total loss. To prevent the French from repairing them in the future, the Italians inflicted further damage on the wrecks, including cutting their main-battery guns. They then began [[ship breaking|breaking up]] both vessels, but after the Italian surrender in September 1943, the Germans reasserted control over the port. The Germans then turned ''Strasbourg'' back to Vichy control, who placed the ship in a state of conservation in the Bay of Lazaret, hoping to repair the ship after the war. She was then bombed and sunk again by American aircraft after [[Operation Dragoon]], the Allied invasion of southern France. ''Dunkerque'' was also bombed several times in the final years of the war.{{sfn|Jordan & Dumas|p=93}}{{sfn|Garzke & Dulin|p=50}}

After falling under Free French control in October 1944, ''Strasbourg'' was raised again but by that point was beyond repairing. Instead, she was retained as a target for underwater weapons tests. Little else was done with either wreck for more than a decade; in March 1955, ''Strasbourg'' was condemned and renamed ''Q45'' before being sold for [[scrap]] in May. ''Dunkerque'' became ''Q56'' in September but remained extant until September 1958, when she, too, was sold to ship breakers.{{sfn|Jordan & Dumas|p=93}}{{sfn|Dumas|p=75}}

== Citations ==
{{Commons category}}
{{reflist|20em}}

==References==
* {{cite book
  |last=Dumas
  |first=Robert
  |title=Les cuirassés Dunkerque et Strasbourg
  |trans-title=The Battleships Dunkerque and Strasbourg
  |language=fr
  |publisher=Marine Éditions
  |year=2001
  |location=Paris
  |isbn=978-2-909675-75-6
  |ref={{sfnRef|Dumas}}
  }}
* {{cite book
  |last=Friedman
  |first=Norman
  |title=Naval Weapons of World War One: Guns, Torpedoes, Mines and ASW Weapons of All Nations: An Illustrated Directory
  |publisher=Seaforth
  |location=Barnsley
  |year=2011
  |isbn=978-1-84832-100-7
  |author-link=Norman Friedman
  |ref={{sfnRef|Friedman}}
  }}
* {{Cite book
 | editor-last = Gardiner
 | editor-first = Robert
 | title = The Eclipse of the Big Gun
 | publisher = Naval Institute Press
 | location = Annapolis
 | year = 1992
 | isbn = 978-0-85177-566-1
 | ref = {{sfnRef|Gardiner}}
  }}
* {{cite book
  |last1=Garzke
  |first1=William H. Jr.
  |last2=Dulin
  |first2=Robert O. Jr.
  |title=British, Soviet, French, and Dutch Battleships of World War II
  |year=1980
  |publisher=Jane's
  |location=London
  |isbn=978-0-7106-0078-3
  |ref={{sfnRef|Garzke & Dulin}}
  | name-list-style=amp
  }}
* {{cite book
  |last1=Jordan
  |first1=John
  |last2=Dumas
  |first2=Robert
  |title=French Battleships 1922–1956
  |publisher=Seaforth Publishing
  |isbn=978-1-84832-034-5
  |year=2009
  |location=Barnsley
  |ref={{sfnRef|Jordan & Dumas}}
  | name-list-style=amp
  }}
* {{cite book
  |last=Labayle-Couhat
  |first=Jean
  |title=French Warships of World War I
  |publisher=Ian Allan
  |location=London
  |year=1974
  |isbn=978-0-7110-0445-0
  |ref={{sfnRef|Labayle-Couhat}}
  }}
* {{cite book
  | last = Roberts
  | first = John
  | chapter = France
  | pages = 255–279
  | editor1-last = Gardiner
  | editor1-first = Robert
  | editor2-last = Chesneau
  | editor2-first = Roger
  | year = 1980
  | title = Conway's All the World's Fighting Ships 1922–1946
  | location = Annapolis
  | publisher = Naval Institute Press
  | isbn = 978-0-85177-146-5
  | ref = {{sfnRef|Roberts}}
  | name-list-style=amp
  }}
* {{cite book
  | last = Rohwer
  | first = Jürgen|author-link=Jürgen Rohwer
  | year = 2005
  | title = Chronology of the War at Sea 1939–1945 – The Naval History of World War Two
  | publisher = Chatham Publishing
  | location = London
  | isbn = 978-1-59114-119-8
  | ref = {{sfnRef|Rohwer}}
  }}

{{Dunkerque class battleship}}
{{French battleships}}
{{WWII French ships}}
{{Late battleships}}

{{DEFAULTSORT:Dunkerque Class Battleship}}
[[Category:Battleship classes]]
[[Category:Battlecruiser classes]]
[[Category:Dunkerque-class battleships| ]]
[[Category:World War II battleships of France]]
[[Category:Ship classes of the French Navy]]