Golden Journal No. 50:
Les Portes-Avions
French Carrier Joffre
by Mike Bennighof, Ph.D.
May 2024

The converted battleship Béarn had been an unsatisfactory aircraft carrier, not even able to remain in service to provide much of a training capability. But France’s Marine Nationale remained dedicated to the concept of carrier aviation, and sought new, modern carriers that could do the things that Béarn could not.

Design PA16, presented by the Service Technique des Constructions Navale (STCN) in 1934, took a very different approach than previous design studies. The new design emphasized speed, to allow the ship to operate with the battle cruisers, light cruisers and contre-torpilleurs of the Force de Raid. PA16 featured a massive island structure to starboard, with its flight deck offset to port to balance the weight. PA16, originally set at 15,000 tons’ displacement, grew to 18,000 during the design phase. The ship would be built for speed rather than protection, clocking 33 knots (at least, that was the intention) on 120,000 horsepower generated by a set of geared turbines.

The financial impact of the Great Depression, which struck France later than the rest of Europe and lingered longer, delayed action on orders for new aircraft carriers, as did a fierce bureaucratic struggle between the Marine Nationale and the Air Ministry, formed in 1928. The Navy was left with control of the handful of planes aboard its lone carrier, and the floatplanes equipping battleships and cruisers; the Ministry oversaw all other military flight in France, and it was in no mood to see the Navy’s tiny carrier-aircraft fiefdom expanded.

By 1936, the Navy had exerted its bureaucratic muscle to bring more air activities under its control, and the Germans laid down the carrier Graf Zeppelin at the end of the year with the intent to build a sister for her. The Marine Nationale obtained authorization for its own pair of carriers in December 1936 on the heels of the German announcement, but funding did not appear until well into 1937. The first carrier, to be named Joffre for Marshal of France Joseph Joffre, was laid down in November 1938 at the Penhoët yard in St.-Nazaire. Her sister, Painlevé, named for wartime Prime Minister Paul Painlevé, would be laid down on the same slipway once Joffre had been launched.

Laying Joffre’s keel. 22 November 1938.

Joffre would have had two hangar decks, a full-length hangar below the flight deck (though not offset) and a smaller lower hangar almost exactly half the length of the upper hangar. As with Béarn, only the upper hangar would house operable aircraft, with the lower hangar devoted to workshops and replacement aircraft. Joffre’s design called for what the French called “double-ended” air operations; she could both launch and recover planes from either the bow or stern end of her flight deck (though not both at once). That would allow the ship to continue to fly her planes even after damage to her flight deck.

She was intended to carry 40 aircraft, and the Marine Nationale ordered 81 Grumman G36 planes (an export version of the F4F Wildcat modified to French requirements) for the ships’ fighter component. Joffre did not have a catapult in her design, and the aircraft capacity seems to be based on the hangars alone, without the provision of an American-style deck park. The Royal Navy provided technical assistance, and the French architects corrected a flaw of British carriers, making the hangars roomy enough to allow aircraft maintenance.

The hull form was based closely on France’s last heavy cruiser, Algérie, with the power plant modeled closely on that of the proposed light cruiser De Grasse, laid down in August 1939. Like contemporary French cruisers and large destroyers, Joffre followed the “unit” layout of her machine, with boiler and turbine rooms interspersed to that a single hit would be unlikely to leave the ship dead in the water. She had belt armor of 105mm, a torpedo belt inside of it at 55mm thick, and an armored deck of 70mm – all roughly equivalent to the heavy cruiser Algérie, considered one of the better-protected ships of her type.

Joffre carried eight 130mm Model 1931 dual-purpose guns in four Model 1932 twin gunhouses, the same as carried by the battle cruiser Dunkerque. A super-firing pair of gunhouses were fitted at the forward and aft ends of the island, with gunnery directors on the island’s roof. Each gunhouse had a pair of ammunition hoists, one for anti-aircraft rounds and one for anti-surface rounds.

For close anti-aircraft defense, Joffre would have four twin ACAD (Automatique Contre-Avions Double) 37mm/70-caliber Model 1935 anti-aircraft guns. This was a sophisticated system featuring high muzzle velocity (so that the projectile reached its target with minimal flight time, improving accuracy) and a heavy bursting charge (so that a single shell could hopefully bring down the target aircraft). Those conflicting requirements led to adoption of a complicated loading system with six-round cartridge boxes brought up from the ready-use rack located a deck below the gun mount itself.

That high velocity and heavy shell added up to severe vibrations, and so the director and rangefinder were located in a separate tower directly behind the gun mount. The gun captain controlled the weapon from there by remote control (one director tower sometimes controlled two separate gun mounts). The problematic velocity/shell weight combination, plus the high rate of fire (over 100 rounds per minute in sustained firing) also resulted in rapid barrel wear, within minutes at maximum rate of fire (172 rounds per minutes). Only one mount was completed before the fall of France; it was deployed at Dunkirk on a small French warship and appears to have performed well.

Though some sources claim that work on Joffre halted with the outbreak of war, this is not true. It slowed, but continued until mid-June 1940 when German troops approached St.-Nazaire. Her sister Painlevé had not been formally laid down, awaiting Joffre’s launch to clear the slipway, but the Penhoët yard had begun collecting materials to start. In April 1940 the proposed fast battleship Alsace was allotted to Joffre’s slipway instead, with Painlevé delayed. An authorized third sister was cancelled at the same time.

All three carriers appear in Golden Journal No. 50: Les Portes-Avions, with the third ship named Delcassé for the Germanophobic French foreign minister Théophile Delcassé, who forged France’s pre-war alliances with Britain and Russia and as Navy Minister oversaw the laying down of France’s first dreadnoughts.

Joffre would have given the Force de Raid a very capable ship; with an American-style deck park she probably could have operated 60 aircraft. Given the uselessness of Béarn in the training role (or any other role), a good part of her time would have been devoted to qualifying her pilots for carrier operations. But once given a solid air group, she would have been formidable in her intended roles of commerce protection and countering the German aircraft carriers.

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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, three children, and new puppy. He misses his lizard-hunting Iron Dog, Leopold.

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