Béarn () was an aircraft carrier converted from an incomplete for the (French Navy) during the 1920s. Entering service in 1928, the navy intended to use her to develop tactics and techniques for carrier aviation. The only aircraft carrier France produced until after World War II, the ship played a minor role in early stages of the war, training in home waters and conducting pilot training.
In late May 1940 Béarn ferried gold to purchase aircraft from the United States, but she was diverted to Martinique in the French West Indies when the French armistice with Germany was signed in June. Under pressure from the United States, which was worried about the Germans taking control of her if she returned to France, the carrier remained there for the next four years. To placate the Americans, the local commander agreed to have her immobilized in mid-1942. The Vichy French government ordered him to sabotage the ship in May 1943 and he ultimately complied by having Béarn run aground.
She was towed to Puerto Rico after the islands joined the Free French later that year for preliminary repairs that would allow her to steam under her own power to New Orleans, Louisiana, to be converted into an aircraft ferry. The conversion was completed in early 1945; on her first trip with a load of aircraft she collided with another ship and had to divert to French Morocco for emergency repairs. Full repairs took almost six months and she then transported personnel and equipment between Metropolitan France and French North Africa for several months.
In October the ship sailed for French Indochina with aircraft, material and supplies as the French planned to reassert control over their Japanese-occupied colony. Béarn remained there for a year before returning home where she was immediately placed in reserve. Two years later, the ship was reactivated as the flagship of the 's submarine and anti-submarine group and also served as a submarine tender. In 1960 Béarn was hulked and served as a barracks ship until she became so uneconomical that a replacement vessel was constructed in 1966. She was sold for scrap the following year.
Description as a battleship
The Normandie-class ships were long at the waterline, and long overall. They had a beam of and a mean draft of at full load. They were intended to displace at normal load and at deep load. The ships would have had a crew of 44 officers and 1,160 enlisted men when serving as a flagship.Jordan & Caresse, pp. 191–192
Unlike her sister ships, Béarn was intended to be equipped with two sets of Parsons steam turbines, each driving a pair of propeller shafts using steam provided by 28 Niclausse boilers. The engines were rated at and were designed for a speed of , although use of forced draft was intended to increase their output to and the maximum speed to .Jordan & Caresse, p. 201 The ships were designed to carry enough coal and fuel oil to give them an estimated range of at .
Armament and armor The main battery of the Normandie class consisted of a dozen Canon de Modèle 1912M guns mounted in three quadruple turrets. One turret was placed forward, one amidships, and one aft of the superstructure, all on the centerline. The ships would also have been equipped with a secondary armament of 24 Canon de Modèle 1910 guns, each singly mounted in casemates near the main-gun turrets. Anti-aircraft defense probably would have been provided by four Canon de Modèle 1902 AA guns. The ships also would have been equipped with six underwater torpedo tubes, three on each broadside.Jordan & Caresse, pp. 193–197
The waterline armor belt of the Normandie-class ships extended almost the entire length of the hull, save for at the stern. The thickest portion of the armor protected the hull between the barbettes of the end turrets and was thick. From the forward barbette to the bow, the plates progressively reduced in thickness from , aft of the rear turret, the armor plates were progressively reduced in thickness from 260 millimeters to . The turrets were protected with an armor thickness of 300 millimeters on their faces, on the sides, and 100 millimeters on the roof. The casemates were defended by 160-millimeter armor plates. The portions of the barbettes that extended outside the upper armor were protected by plates. The sides of the conning tower were thick and its roof was also 100 millimeters thick. The lower armored deck ranged in thickness from with the thickest portion of the deck where it sloped to meet the bottom of the armor belt. The upper armored deck was thick with the thickest part on the outer edges.Jordan & Caresse, pp. 198–200
The torpedo bulkhead of the Normandies consisted of a nickel-steel plate, faced with a plate of corrugated mild steel that was intended to absorb the shock wave from a torpedo warhead's detonation. Abreast the boiler rooms were very deep coal bunkers that were also intended to help absorb a torpedo detonation.Jordan 2020, p. 16
Construction and conversion Béarn, named for the historic province of Béarn,Silverstone, p. 88 was ordered on 30 December 1912Roberts, p. 357 and was laid down at the Forges et Chantiers de la Méditerranée shipyard in La Seyne on 10 January 1914. The outbreak of World War I in August 1914 interrupted construction, which was halted for the duration of the conflict.Smigielski, p. 198 By that time, work on Béarn had not significantly progressed: her hull was only 8–10 percent complete and her engines were only 25 percent finished. Her boilers were 17 percent assembled, and her turrets were 20 percent completed.Preston, p. 68 The hull was launched on 15 April 1920 to clear the slipway, though the had not yet decided what to do with it.Jordan 2020, p. 9
That year, a French delegation visited the British aircraft carrier , and out of this visit came a proposal to convert one of the incomplete Normandie-class battleships into an aircraft carrier, which was designated Project 171. The first step was to conduct trials using Béarns hull which was only complete up to the lower armored deck and lacked her belt armor and propulsion machinery. A wooden platform was built on the lower deck with an improvised arresting gear system that was weighted down with sandbags. Paul Teste conducted the first tests in October using British Sopwith 1½ Strutters. Further trials were conducted the following year with the Hanriot HD.3.
Still undecided on whether to complete the ship as either a battleship or an aircraft carrier, the 's hand was forced when the Washington Naval Treaty was signed on 6 February 1922 and ruled out the former possibility. On 18 April the decided that Béarn, rather than any of her sisters, would be converted into an aircraft carrier because her construction was the least advanced and would thus be the cheapest to convert.Polmar, p. 65 Her four sisters, which were closer to completion, were instead broken up for scrap. Much of the equipment from these ships was used to complete Béarn and several cruisers that had been ordered in 1922.Le Masson, p. 419 A contract for the conversion was signed with her builder on 4 August 1923 for 66.33 million French francs.
General characteristics and machinery Béarn was long between perpendiculars and long overall. She had a beam of at the waterlineJordan 2020, p. 14 and at the flight deck. She displaced at standard load and at full load, which gave her a draft of .Jordan 2011, p. 181 A retractable, four-story charthouse was installed at the forward end of the flight deck; when retracted there were views forward and to the sides underneath the flight deck. Including the airgroup, her crew numbered 45 officers and 830 enlisted men.Jordan 2020, pp. 14, 17–18
The decided to revert to the mixed propulsion machinery of Béarns sisters rather than use her intended pair of direct-drive steam turbines and used the machinery from the lead ship of the class, Normandie. One set of Parsons turbines drove the two inner propeller shafts and two vertical triple-expansion steam engines were on the outer shafts for low-speed cruising. This was intended to reduce fuel consumption at cruising speeds, as direct-drive turbines are very inefficient at moderate to low speeds. The engines were rated at a total of using steam supplied by a dozen new oil-burning Normand boilers that had a working pressure of , which gave Béarn a maximum speed of . The boiler uptakes were trunked into a single funnel integrated into the island on the starboard side of the flight deck. A large vented chamber, nicknamed the (lamp base), was fitted on the side of the hull below the funnel to mix cooler air with the hot boiler exhaust to reduce air turbulence over the flight deck. The ship carried a maximum of of fuel oil which gave her a range of at a cruising speed of . Electric power was provided by four steam-powered dynamos; a pair of diesel generators were used when the ship was in harbor.Jordan 2020, pp. 10–11, 14
Aviation facilities
The ship's flight deck was long and it had a maximum width of . The deck itself was composed of two overlapping plates covered by of African teak. She retained the primitive arresting gear used during her trials when completed, but it was replaced during her first refit. The carrier was also fitted with a crane aft of the island that had the secondary task of handling the pair of seaplanes that were embarked for use when the ship was in harbor.Jordan 2020, pp. 18–21
Béarn was fitted with three electrically powered elevators that transferred aircraft between the flight deck and the upper hangar. The forward elevator could lift and measured long and wide as it was intended to handle only fighters. The elevator was unusual as it had a two-story configuration so that aircraft could be flown off while it was in the lowered position. The center elevator was intended for reconnaissance aircraft with their wings deployed and was in size. It could handle , although it was slow, requiring three minutes for a complete cycle. To enable flight operations to continue while it was at the hangar-deck level, the open elevator shaft was provided with heavy clamshell doors at the flight-deck level. The aft elevator was 15 meters square and was designed for torpedo bombers. It had the same capacity as the center elevator, but was even slower, requiring five minutes to cycle, and had the same clamshell doors at the flight-deck level.Jordan 2020, pp. 18–20
The ship was designed with two hangar decks, of which only the upper hangar could be used for aircraft operations as the lower hangar was dedicated to workshops and aircraft assembly and storage facilities. The hangars had nominal widths of , but equipment and ready-use weapon storage racks reduced the effective width to 15 meters. The upper hangar had a height of except in the forward section, which was intended for use by fighters, where it was reduced to by an extra deck that contained the berthing for the air group. Both hangars were subdivided into four sections by asbestos fire curtains and equipped with three overhead rails with which to move aircraft and other heavy equipment. The lower hangar was equipped with three large hatches at the base of the elevator shafts for access to the upper hangar. The bottoms of the elevators were fitted with rails that matched the overhead rails in the hangars; aircraft would be hung from the rails and the elevators would be raised or lowered as needed. Béarn stored of aviation gasoline in three compartments within the armored citadel which were filled with inert nitrogen gas as a fire suppressant measure.Jordan 2020, pp. 14, 22–23