French submarine Achéron

Achéron was a French Navy Redoutable-class submarine of the M6 series commissioned in 1932. She participated in World War II, first on the side of the Allies from 1939 to June 1940, then in the navy of Vichy France. She was scuttled in November 1942.

Characteristics
Achéron was part of a fairly homogeneous series of 31 deep-sea patrol submarines also called "1,500-tonners" because of their displacement. All entered service between 1931 and 1939.

The Redoutable-class submarines were 92.3 m long and 8.1 m in beam and had a draft of 4.4 m. They could dive to a depth of 80 m. They displaced 1,572 t on the surface and 2,082 t underwater. Propelled on the surface by two diesel engines producing a combined 6,000 hp, they had a maximum speed of 18.6 kn. When submerged, their two electric motors produced a combined 2,250 hp and allowed them to reach 10 kn. Also called "deep-cruising submarines", their range on the surface was 10,000 nmi at 10 kn. Underwater, they could travel 100 nmi at 5 kn.

Construction and commissioning
Laid down at Ateliers et Chantiers de la Loire in Saint-Nazaire, France, on 4 or 24 September 1927 with the hull number Q150, Achéron was launched on 6 August 1929. She was commissioned on 22 February 1932.

Service history
In 1937, Achéron received orders to make a cruise to Argentina in company with her sister ships FRENCH SUBMARINE Agosta, FRENCH SUBMARINE Bévéziers, and FRENCH SUBMARINE Fresnel.

French Navy
At the start of World War II in September 1939, Achéron was assigned to the 3rd Submarine Division in the 2nd Squadron — a component of the 1st Flotilla — based at Toulon, France. Her sister ships FRENCH SUBMARINE Actéon, Fresnel, and FRENCH SUBMARINE Protée made up the rest of the division. In December 1939, Achéron joined Fresnel and their sister ships FRENCH SUBMARINE Le Héros and FRENCH SUBMARINE Redoutable in searching the central Atlantic Ocean for the German supply ship GERMAN TANKER Altmark. Agosta and Béveziers, which were returning to France from the French West Indies, also joined in the search.

At the beginning of February 1940, the 3rd Submarine Division transferred briefly to Casablanca in French Morocco and on 6 February 1940 began patrols off the Canary Islands, where the Allies believed that German cargo ships had taken refuge at the beginning of the war and were serving as supply ships for German U-boats. During these patrols, Achéron opened fire with her deck gun on a 5,265-gross register ton steam cargo ship that her crew suspected of being a German blockade runner, forcing the ship to stop in the Atlantic Ocean at 34.41667°N, -18.13333°W. Crewmen from Achéron boarded the ship and determined that she was the British merchant ship SS Somme, after which Achéron allowed her to proceed.

On 12 April 1940, the 3rd Submarine Division was transferred to the Mediterranean Sea, based first at Bizerte in Tunisia. While Fresnel remained at Bizerte, the division′s other submarines then transferred to Beirut in the French Mandate for Syria and Lebanon, from which they operated under the command of the British Commander-in-Chief, Mediterranean Fleet, Admiral Andrew Cunningham at Alexandria, Egypt. Achéron patrolled in the Eastern Mediterranean in the approaches to Beirut.

German ground forces advanced into France on 10 May 1940, beginning the Battle of France, and Italy declared war on France on 10 June 1940 and joined the invasion. On the day Italy entered the war, British submarines based at Beirut departed for operations in the Aegean Sea off the Dardanelles and in the Tobruk area off the coast of Libya, and on 11 June the French submarines FRENCH SUBMARINE L'Espadon, FRENCH SUBMARINE Phoque, and FRENCH SUBMARINE Protée also departed to operate in the Dodecanese, leaving only Achéron to defend the approaches to Beirut. On 16 June 1940, an Italian torpedo boat fired a torpedo at Achéron, but missed.

The Battle of France ended in France's defeat and armistices with Germany on 22 June 1940 and with Italy on 24 June, both of which went into effect on 25 June 1940. Achéron — by then assigned to the 3rd Submarine Division in the 3rd Squadron in the 1st Flotilla — was recalled to Beirut.

Vichy France
After France's surrender, Achéron served in the naval forces of Vichy France. Her batteries and those of her sister ship FRENCH SUBMARINE Actéon — which also was at Beirut — were in poor condition, but repairing or replacing them was impossible at Beirut. Escorted by the netlayer FRENCH NETLAYER Le Gladiateur, the two submarines departed Beirut on 16 October 1940 bound for Toulon, which they reached on 24 October 1940. At Toulon, Achéron was placed under guard and maintained in a disarmed and unfueled state in accordance with the terms of the Armistice of 22 June 1940. By 1 November 1942, still in this status at Toulon, Achéron had been assigned to the 1st Submarine Group along with her sister ships FRENCH SUBMARINE L'Espoir, FRENCH SUBMARINE Le Glorieux, and FRENCH SUBMARINE Vengeur.

Loss
Achéron was at Toulon when Germany and Italy occupied the Free Zone (Zone libre) of Vichy France on 27 November 1942, and she was among the French vessels scuttled at Toulon to prevent their seizure by Germany when German forces entered the naval base that day, sinking in Dock No. 3 of the Vauban Grand Docks.

The Germans seized Achéron and handed her over to the Italians for scrapping. Her wreck lay in a position where her stern hindered the closing of Dock No. 3, so divers cut her stern. The Italians refloated her on 26 June 1943, but she was still at Toulon when Italy surrendered to the Allies on 9 September 1943. The Germans seized her and earmarked her for scrapping, but 88 American bombers dropped 240 ST of bombs on the Toulon Arsenal and sank her on 24 November 1943 before she could be scrapped.