The Dunkerque class was a pair of fast battleships built for the French Navy in the 1930s; the two ships were Dunkerque and Strasbourg. They were the first French battleships built since the Bretagne class of pre-World War I vintage, and they were heavily influenced by the Washington Treaty system that limited naval construction in the 1920s and 1930s. French battleship studies initially focused on countering fast Italian heavy cruisers, leading to early designs for small, relatively lightly protected capital ships. But the advent of the powerful German Deutschland-class cruisers 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 330 mm (13 in) guns that were concentrated in two quadruple gun turrets forward, with armour sufficient to defeat the Deutschlands' 283 mm (11.1 in) guns. Strasbourg was completed to a slightly modified design, receiving somewhat heavier armour in response to new Italian Littorio-class battleships. Smaller and less heavily armed and armoured than all other treaty battleships, the Dunkerques have sometimes been referred to as battlecruisers.

Quick Facts Class overview, General characteristics ...

Dunkerque
Class overview
Name	Dunkerque class
Operators	French Navy
Preceded by	Lyon class (planned) Bretagne class (actual)
Succeeded by	Richelieu class
Built	1932–1938
In service	1937–1942
Completed	2
Lost	2
General characteristics [1]
Class and type	Fast battleship
Displacement	26,500 t (26,100 long tons) (standard) 35,500 t (34,900 long tons) (deep load)
Length	214.5 m (704 ft)
Beam	31.1 m (102 ft)
Draft	8.7 m (29 ft)
Installed power	107,500 shp (80,200 kW) 6 Indret boilers
Propulsion	4 × screws 4 × geared steam turbines
Speed	29.5 knots (54.6 km/h; 33.9 mph)
Range	7,850 nmi (14,540 km; 9,030 mi) at 15 knots (28 km/h; 17 mph) 2,450 nmi (4,540 km; 2,820 mi) at 28.5 knots (52.8 km/h; 32.8 mph)
Crew	81 officers 1,300 enlisted men
Armament	8 × 330 mm (13 in) guns 16 × 130 mm (5.1 in) DP guns 8 × 37 mm (1.5 in) AA guns 32 × 13.2 mm (0.52 in) AA machineguns
Armour	Belt armour: 225 mm (8.9 in) Main deck: 115 mm (4.5 in) Gun turrets: 330 mm (13 in) Conning tower: 270 mm (10.6 in)
Aircraft carried	2 floatplanes

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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 Dunkerques, which was tasked with hunting down the Deutschlands that were expected to operate in the Atlantic as commerce raiders. 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 Dunkerques 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 scuttled the fleet in Toulon. Both ships were badly damaged and were handed over to Italian control, where they were partially broken up. Their hulks, which were bombed by American aircraft in 1944, were eventually sold for scrap in the 1950s.

Wary of another naval arms race similar to the Anglo-German race that was seen as 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 175,000 long tons (178,000 t) of total battleship tonnage; French resistance to a halt on battleship construction, in light of the obsolescent Courbet and Bretagne-class battleships that formed the core of its fleet, led to an exception for France (and Italy) to replace 70,000 long tons (71,000 t) worth of battleships during the moratorium, to be laid down in 1927 and 1929. Maximum displacement of any new battleship was restricted to 35,000 long tons (36,000 t) at standard displacement.^[2][3]

In 1926, the Chief of the Naval General Staff, Admiral Henri Salaun, requested a new capital ship design with a displacement of 17,500 long tons (17,800 t), intended to counter the new generation of Italian heavy cruisers. The first of these Italian vessels, the two Trento-class cruisers, 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 battery of eight 305 mm (12 in) guns mounted in two quadruple gun turrets, 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 203 mm (8 in) 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 tons. The concept was strongly influenced by the British Nelson-class battleships, which mounted their battery entirely forward to save armour weight.^[4]

The German Deutschland-class cruisers, which were armed with a battery of six 283 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 36,000-long-ton (37,000 t) design. These ships were in most respects an enlarged version of the Suffren class of heavy cruisers then being built. The increase in displacement brought with it a third quadruple 305 mm turret placed aft and heavier armour protection in a version capable of 33 knots (61 km/h; 38 mph), while a slower 27-knot (50 km/h; 31 mph) ship was to be armed with six 406 mm (16 in) 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.^[5]

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 25,000 long tons (25,000 t)—the ceiling sought by the British—and a minimum 23,333 long tons (23,707 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 Deutschlands; this led to renewed concerns over the level of armour protection, which was still too thin to defeat the German 283 mm gun. After pressure from the French parliament over the perceived weakness of the design, the Chief of the Naval Staff issued a new set of requirements, including an increase in standard displacement to 25,000 long tons (25,000 t), an armament of eight 330 mm guns, and armour sufficient to resist 283 mm projectiles.^[6]

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 26,000 long tons (26,000 t) and finally to 26,500 long tons (26,900 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 mm fire at expected battle ranges, but it was also capable of defeating the 305 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 381 mm (15 in) 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 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 Richelieu class.^[7]

The Dunkerque-class ships' relatively small size and light armament and emphasis on speed rather than protection, especially compared to the other treaty battleships of the period, has led some to classify them as battlecruisers.^[8]

The two ships differed slightly in their dimensions; both were 209 m (686 ft) long between perpendiculars, while Dunkerque was 215.14 m (705.8 ft) long overall while Strasbourg was 215.5 m (707 ft) overall. The two ships both had a beam of 31.1 m (102 ft). Dunkerque displaced 26,500 long tons (26,900 t) standard, 30,260 long tons (30,750 t) normally, and 34,900 long tons (35,500 t) fully loaded. Strasbourg was slightly heavier, at 27,300 long tons (27,700 t) standard, 31,070 long tons (31,570 t) normally, and 35,810 long tons (36,380 t) at full load, with the difference being the result of increased armour protection. Draft for Dunkerque measured 8.57 m (28.1 ft) normally and increased to 9.71 m (31.9 ft) at full load, and Strasbourg drew 8.73 m (28.6 ft) at normal loading and 9.89 m (32.4 ft) at full load.^[9]

Dunkerque had a crew of 81 officers and 1,300 sailors, while Strasbourg's crew consisted of 32 officers and 1,270 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 pinnaces, whaleboats, launches, and dinghies. Steering was controlled by a single rudder; the rudder had a range of train from 0 to 32 degrees from the centreline, but had a tendency to jam when turned further than 25 degrees. The rudder was electrically operated, but the ships also had manual controls in the event of a power failure.^[10]

The ships carried three Loire 130 seaplanes for use as reconnaissance and spotter aircraft on the fantail, and the aircraft facilities consisted of a 22 m (72 ft) steam catapult, a hangar, and a crane to handle the floatplanes. The hangar had two storeys 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.^[11][12]

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 Naval Review for the coronation of King George VI and Queen Elizabeth. In early 1938, Dunkerque toured France's West African 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.^[25][26]

During the Sudetenland Crisis with Germany in early April 1939, Dunkerque was sent to cover the return of the training cruiser Jeanne d'Arc 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 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 raiders.^[27][28]