Dunkerque and Strasbourg formed the French Navy's 1ère Division de Ligne (1st Division of the Line) prior to the Second World War. The two ships searched for German commerce raiders in the early months of the war, and Dunkerque also participated in convoy escort duties. The ship was badly damaged during the British attack at Mers-el-Kébir after the Armistice that ended the first phase of France's participation in World War II, but she was refloated and partially repaired to return to Toulon for comprehensive repairs. Dunkerque was scuttled in November 1942 to prevent her capture by the Germans, and subsequently seized and partially scrapped by the Italians and later the Germans. Her wreck remained in Toulon until she was stricken in 1955, and scrapped three years later.
The French Navy's design staff spent the decade following the 1922 Washington Naval Treaty attempting to produce a satisfactory design to fill 70,000 tons as allowed by the treaty. Initially, the French sought a reply to the Italian Trento-class cruisers of 1925, but all proposals were rejected. A 17,500-ton cruiser, which could have handled the Trentos, was inadequate against the old Italian battleships, however, and the 37,000-ton battlecruiser concepts were prohibitively expensive and would jeopardize further naval limitation talks. These attempts were followed by an intermediate design for a 23,690-ton protected cruiser in 1929; it was armed with 305 mm (12.0 in) guns, armoured against 203 mm (8.0 in) guns, and had a speed of 29 kn (54 km/h; 33 mph). Visually, it bore a profile strikingly similar to the final Dunkerque.
The German Deutschland-class cruisers became the new focus for French naval architects in 1929. The design had to respect the 1930 London Naval Treaty, which limited the French to two 23,333-ton ships until 1936. Drawing upon previous work, the French developed a 23,333-ton design armed with 305 mm (12.0 in) guns, armoured against the German cruisers' 280 mm (11 in) guns, and with a speed of 30 kn (56 km/h; 35 mph). As with the final Dunkerque, the main artillery was concentrated entirely forward. The design was rejected by the French parliament in July 1931 and sent back for revision. The final revision grew to 26,500 tons; the 305 mm guns were replaced by 330mm/50 Modèle 1931 guns, the armour was slightly improved, and the speed slightly decreased. Parliamentary approval was granted in early 1932, and Dunkerque was ordered on 26 October.
Dunkerque displaced 26,500 t (26,100 long tons) as built and 35,500 t (34,900 long tons) fully loaded, with an overall length of 214.5 m (703 ft 9 in), a beam of 31.08 m (102 ft 0 in) and a maximum draft of 8.7 m (28 ft 7 in). She was powered by four Parsons geared steam turbines and six oil-fired Indret boilers, which developed a total of 112,500 shaft horsepower (83,900 kW) and yielded a maximum speed of 29.5 kn (54.6 km/h; 33.9 mph). Her crew numbered between 1,381 and 1,431 officers and men. The ship carried a pair of spotter aircraft on the fantail, and the aircraft facilities consisted of a steam catapult and a crane to handle the floatplanes. The floatplanes were initially Gourdou-Leseurre GL-832 HY, and later Loire 130.
She was armed with eight 330mm/50 Modèle 1931 guns arranged in two quadruple gun turrets, both of which were placed in a superfiring pair forward of the superstructure. Her secondary armament consisted of sixteen 130 mm (5.1 in) /45 dual-purpose guns; these were mounted in three quadruple and two twin turrets. The quadruple turrets were placed on the stern, and the twin turrets were located amidships. Close range antiaircraft defense was provided by a battery of eight 37 mm (1.5 in) guns in twin mounts and thirty-two 13.2 mm (0.52 in) guns in quadruple mounts. The ship's belt armor was 225 mm (8.9 in) thick amidships, and the main battery turrets were protected by 330 mm (13 in) of armor plate on the faces. The main armored deck was 115 mm (4.5 in) thick, and the conning tower had 270 mm (11 in) thick sides.