The Middle Sea:
Duquesne Class Cruisers
by Mike Bennighof, Ph.D.
August 2023

For their next heavy cruiser after the disappointing Duquesne class, France’s Marine Nationale sought a very similar ship – design work had to commence before the previous class had even been laid down. Not all of the shortcomings of Duquesne were fully understood when her successor, Suffren, was drafted.

One thing that did seem obvious is that the new heavy cruiser needed better protection, even if it came at the cost of speed. Most obviously, she added a 50mm armored belt, which while not particularly thick (the Italian Trento class had a belt of 70mm), represented a significant improvement over Duquesne’s utter lack of any protection beyond splinter-proofing.

For additional protection, the Service Technique des Constructions Navale (SCTN) adopted a novel means of working around the Washington treaty limits on displacement. Fuel didn’t count toward the total, and so Suffren would have 640 tons of coal in bunkers placed outboard of her machinery spaces to provide extra protection. To meet the treaty requirements, the cruiser had two small “cruising boilers” that ostensibly burned the coal, but they don’t seem to have seen any use in that role – burning the coal would mean burning some of the ship’s protection.

The belt was fairly narrow and did not cover the upper part of the hull. Additional armor went over the magazines and the machinery spaces, and a torpedo bulkhead as well. Suffren also had a 25mm armored deck. The weight devoted to armor almost doubled compared to Duquesne, but still fell far short of that in contemporary Italian or even British heavy cruisers (the latter referred to as “tin-clads”). The gun turrets’ protection remained identical to those of Duquesne.

Armament remained identical to Duquesne: eight Model 1924 203mm guns in the same four twin turrets, eight 75mm Model 1922 high-angle guns, plus eight more 37mm Model 1925 anti-aircraft guns, also in single mountings. Like Duquesne she had six torpedo tubes in two triple mounts, one on either beam with three reloads carried in the amidships torpedo workshop located between the mounts.

Heavy cruiser Suffren at Hampton Roads, Virginia. October 1931.

To allow for the additional armor, such as it was, the power plant had to be reduced in size and output, and Suffren’s pumped out just under 89,000 horsepower, compared to the 120,000 of Duquesne (the power trials don’t seem to have included the output of the ridiculous “cruising boilers”). That was good for just 31 knots, making Suffren notably slower than most Treaty cruisers even when new.

She had two catapults, and though her design specs called for four floatplanes to be carried, she usually only embarked two, which rested on the catapults when not in use.

The Brest Arsenal laid down Suffren in April 1926, and she commissioned in March 1930. For the next decade she made training cruises and Mediterranean deployments, before heading to French Indo-China in the summer of 1939 as the new flagship. She spent the war’s first months in the Indian Ocean, moving to Alexandria in May 1940 to become part of the French squadron there, known as Force X, and a month later the Armistice with Germany led to her demilitarization.

Like the rest of Force X, Suffren joined the Free French movement in May 1943 but played only secondary roles, patrolling the Central Atlantic and spending a full year undergoing a refit – by this point, Suffren had very low priority. She made brief deployments to Indo-China after the war, but was laid up in 1947 and finally scrapped in 1976.

The Marine Nationale laid down another cruiser on the slipway vacated by Suffren in June 1927. Colbert would be a near-sister of Suffren, with the same power plant, armor scheme, main armament, torpedoes, and aircraft arrangements. With the previous cruiser far from even fitting out by the time work began on Colbert, no adjustments could be made based on actual experience with Suffren. But the deck layout of Suffren had already caused concern, with catapults, crane, stowage for spare aircraft, boats and two of the anti-aircraft guns seemingly crammed together too tightly.

Colbert therefore had a revised deck layout amidships; she also swapped newer and more powerful 90mm Model 1926 anti-aircraft guns for the 75mm weapons of Suffren. She still carried the useless “cruising boilers” of Suffren, and the 640 tons of “free” armor in the form of coal.

Heavy cruiser Colbert.

Colbert commissioned in March 1931, and spent the pre-war decade in French waters. She operated in the Mediterranean during the war’s first months, and in June 1940 helped bombard the Italian port of Genoa. She was at Toulon, the major naval base in southern France, when the Franco-German Armistice ended the fighting in late June 1940. Afterwards she conducted a few sorties, but was present in November 1942 when German forces tried to seize the French fleet. Colbert’s crew scuttled her there, also blowing up her guns and setting the ship on fire. The wreck would be scrapped after the war.

The next cruiser, to be named Louvois after Louis XIV’s Minister of War, was laid down a day after Colbert vacated the slipway. A month before the cruiser was launched, Marshal Ferdinand Foch died and the ship received a new name in his honor.

The SCTN opted for much greater changes to this ship, though outwardly she would look very much like Suffren and Colbert. Treaty cruisers built by other navies had begun to appear and the SCTN’s analysts realized that the French were using a much stricter reading of the limitations than were other signatories. The French had been counting things like food and drinking water, as well as ammunition, against the 10,000-ton displacement limit. It appeared that others were not.

Internally, Foch would have an armored “box” surrounding her vitals – magazines and machinery spaces. This still would not be very thick (54mm) and proof only against the guns of enemy destroyers, not against those of comparable heavy cruisers or even light cruisers. This new armored box, or caisson, went just inside the protective coal bunkers, which were retained, but the redundant “cruising boilers” went away since the coal now could not be accessed for use, even if the captain wanted to fire up the cruising boilers with coal rather than oil. The space and weight for the boilers went to additional fuel bunkerage. The coal still was not counted against the ship’s displacement; the Marine Nationale listed the coal bunkers as void spaces.

Foch carried the same armament as Colbert, with a slight re-arrangement of the 90mm guns.  The aircraft complement now officially became just two seaplanes, which was not a change in practical terms. She carried almost twice the armor of Colbert, yet still fell short of international standards.

Foch commissioned in December 1931, and then served in French waters until the outbreak of war in September 1939. She went to Dakar in French West Africa to help in the search for the German armored cruiser Admiral Graf Spee. After that ship’s destruction in December 1939 she returned to Toulon and participated in the brief operations against Italy in June 1940. The Franco-German Armistice later that month found her still at Toulon, and she was scuttled there in November 1942 though she did not burn. The Italian Navy raised her, found her beyond repair and scrapped the wreck in 1943.

The next cruiser, Dupleix, would finally address the problem of immunity against enemy light cruisers’ 6-inch guns (though not the 8-inch guns of heavy cruisers). The additional weight would be offset by a still-more-liberal reading of the Washington definitions, by moving the eight 90mm anti-aircraft guns from single to twin mounts, and from much more extensive use of welded as opposed to riveted construction.

Heavy cruiser Dupleix under construction. Brest Arsenal, November 1929.

Otherwise, she would be very similar to Foch, with the same “caisson” armored scheme, now thickened from 54mm to 60mm to repel 6-inch/152mm fire. The arrival of the Great Depression in France slowed construction considerably; she was laid down more than six months after Foch, and completed two years after the previous ship.

With her near-sister Foch, she hunted for Admiral Graf Spee and bombarded Italy; left at Toulon by the armistice, her crew attempted to scuttle her in November 1942. German soldiers forced their way aboard and ordered some of the French sailors below to close the sea-cocks allowing water into the hull. Instead, they apparently set the ship on fire and she burned for nine days. She would be raised by the Italians, bombed and sunk again by the Americans, and finally scrapped by the French.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and NASA Journalist in Space finalist, he has published a great many books, games and articles on historical subjects; people are saying that some of them are actually good. He lives in Birmingham, Alabama with his wife and three children. He will never forget his Iron Dog, Leopold.

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