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Naval Warfare

FS Surcouf (N N 3)

Ocean-Going Cruiser Submarine [ 1934 ]

Although three of the Surcouf-class cruiser submarines were planned, only the Surcouf herself was completed and put to sea, seeing some action in World War 2.

Authored By: Staff Writer | Last Edited: 11/09/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

Surcouf (N N 3) was a mammoth French-built attack submarine developed and built during the interwar years between World War 1 (1914-1918) and World War 2 (1939-1945). At the time of her completion, she represented the largest (by displacement) submarine ever put to sea, a triumph of French naval engineering. She also carried battleship-caliber 8" deck guns, the largest then allowed on submarines by the Washington Naval Treaty (attempting to control naval escalation between world powers), making her one of the more unique vessels entering World War 2.

Surcouf was ordered in December of 1927, launched in October of 1929 and commissioned in May of 1934. She carried the name of one Robert Surcouf (1773-1827) who built his fortune by prowling the Indian Ocean as a privateer and merchant during the latter half of the 18th century and into the 19th century. He was awarded the "Sabre of Honour" and the "Legion of Honour" during his time at sea. The Surcouf submarine served the French Navy under the pennant number of "N N 3" and was intended as a three-strong class though only the single ship was ever completed - serving primarily in the role of experimental cruiser submarine.

Externally, the Surcouf was given a unique design profile as submarines of the period go. She featured the usual tapering at her bow and stern as well as the flat surface deck with her sail positioned at midships in the usual way. However, her sail was extended forwards to encompass a large main gun emplacement which gave the submarine considerable firepower against surface ships. Railing was set from about the forecastle back to the stern. The vessel displaced at 3,300 tons (short) when surfaced and 4,370 tons (short) when submerged. She featured a length of 361 feet, a beam of 29 feet 6 inches and a draught of 23 feet, 9 inches and was typically staffed with 118 personnel including eight officers. The vessel could be stocked with up to 90 days of food.

Power to the submarine was served by 2 x Sulzer diesel engines which were in use when the vessel was surfaced. Underwater propulsion came from 2 x electric motors. This hybrid configuration was typical of submarines of the time and drove twin screws at the stern. Performance-wise, the vessel could reach surfaced speeds of 18.5 knots and submerged speeds of 10 knots. Her range was 10,000 nautical miles when heading at 10 knots on the surface and featured a submerged range of 70 nautical miles when heading at 4.5 knots. The Surcouf being no exception, submarines of World War 2 were required to surface to recharge batteries and oxygen supplies. This represented one of the more vulnerable moments for the boat when under watch from an enemy.

The Surcouf was an attack submarine by design and she was appropriately very well armed for the role. Her armament suite was led by 8 x 550mm (22") torpedo tubes which fed from a stock of 14 torpedoes. This was supplemented by 4 x 400mm (16") torpedo tubes firing from an onboard stock of 8 torpedoes. Her surface armament included 2 x 203mm (8") guns, 2 x 37mm (1.46") anti-aircraft guns and 4 x 13.2mm (0.52") anti-aircraft guns. The 8" guns utilized a rangefinding director from 60-round magazines.

In addition to her obvious armament, the Surcouf was also able to service 1 x Besson MB.411 floatplane for over-the-horizon reconnaissance, scouting or artillery spotting work. Artillery spotting worked in conjunction with the Surcouf's 8" main guns for more accurate results at extreme ranges. The floatplane was held in a watertight hangar aft of the sail. The wings needed attaching after the aircraft was rolled out. It could then be lowered into the water and launched as normal. The submarine was also able to launch and recover its own motorboat which was housed in a watertight deck well - useful for boarding parties or rescues at sea.©MilitaryFactory.com
The German invasion of France in May of 1940 was part of Adolph Hitler's grand scheme to decimate Western powers en route to total dominion of Europe. This brought a second World War to French soil while Surcouf lay at Brest undergoing refit when the German invasion was made official. She was in a precarious state as one of her engines was inoperable, severely depleting the tactical value of the mighty French submarine. To avoid her capture at the hands of the Germans, the French sailed her to neighboring Britain where she entered Plymouth harbor.

At this point in the war, French defeat seemed certain and the British position was stressed to the point that it need to take action on the remaining French fleet which could be use by the conquering Germans and sympathetic French officers and sailors. The Royal Navy enacted "Operation Catapult" in a plan to subdue the French fleet where it lay and this included a takeover of Surcouf while at Plymouth. The forceful action resulted in the deaths of both Frenchmen and British service personnel for many French did not care to surrender to their historical enemy. Such was the case aboard the Surcouf on July 3rd, 1940 when three British and one French sailor were killed in the fighting.

Regardless, the French fleet was neutralized from further action in the war. The Surcouf remained under British watch for the time being and her refit completed in August of 1940. Command of the vessel was then passed on to the new Free French Navy which stood as the acting navy power of France while Paris lay under German occupation (the German-aligned Vichy French represented the new French government). One of the vessel's first sorties stemmed from Halifax where she was used to escort Allied shipping across the precarious Atlantic under siege from German aircraft and U-boat attacks. Suffering damage from a German aircraft herself, Surcouf was forced to the United States Naval Shipyard at Portsmouth in July of 1941 for repair and refit. She then sailed to New London, Connecticut and made her way back to Halifax in November of 1941.

In December of 1941, Surcouf joined other Free French naval forces in retaking the French archipelago of Saint-Pierre and Miquelon off the coast of Newfoundland. The acting Free French government then sent orders for the Surcouf to set sail for the Pacific Ocean. On December 7th, 1941, naval forces of the Empire of Japan attacked Pearl Harbor, Hawaii and officially committed the United States to war. The US and Britain would then head a years-long bloody campaign to retake Japanese Pacific possessions.

Making her way to the Pacific, the Surcouf was required to traverse the famous Panama Canal. She resupplied at Bermuda and then headed to her target of Tahiti (French Polynesia) via the Canal. However, it is believed that at some point in her journey across the Gulf of Mexico, the surfaced vessel was struck - essentially run over - by the passing American freighter "Thompson Lykes" on the night of February 18th, 1942. The damage was apparently enough to sink Surcouf which claimed all hands to the sea below. The freighter unknowingly continued on while Surcouf sank where she sat. Other sources claim "friendly fire" took her to the depths. In either case, the mighty French submarine was lost forever, her wreck still awaiting discovery even today (October 2013).

In memory of her crew, a memorial was erected at the port city of Cherbourg, France where the Surcouf made her home. The Surcouf was never a wholly a successful design though one of the more successful of the cruiser types put to sea by any nation leading up to World War 2.©MilitaryFactory.com
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Operators National flag of France
National Origin
Project Status
Hull Class
Surcouf (N N 3)

Submerged Attack
Traveling under the surface to search, track, and / or engage or reconnoiter areas.
Maritime Patrol
Active patroling of vital waterways and maritime areas; can also serve as local deterrence against airborne and seaborne threats.
Fleet Support
Serving in support (either firepower or material) of the main surface fleet in Blue Water environments.

361.0 feet
(110.03 meters)
29.5 feet
(8.99 meters)
23.7 feet
(7.22 meters)
Displacement (Submerged)

2 x Sulzer diesel engines delivering 7,600 horsepower; 2 x Electric motors delivering 3,400 horsepower; 2 x shafts.
18.5 knots
(21.3 mph)
Surface Speed
10.0 knots
(11.5 mph)
Submerged Speed
7,003 nm
(8,059 miles | 12,970 km)
1 knot = 1.15 mph; 1 nm = 1.15 mile; 1 nm = 1.85 km

6 x 550mm (22-inch) torpedo tubes; 8 torpedoes
4 x 400mm (16-inch) torpedo tubes; 14 torpedoes
2 x 203mm/50 Modele 1924 cannons
2 x 37mm anti-aircraft cannons
4 x 13.2mm anti-aircraft machine guns

1 x Motorboat held in a watertight deck well.

1 x Besson MB-411 floatplane

Military lapel ribbon for the Cold War period
Military lapel ribbon for early warship designs
Military lapel ribbon for the Falklands War
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Korean War
Military lapel ribbon representing modern aircraft
Military lapel ribbon for the Attack on Pearl Harbor
Military lapel ribbon for the Russian Invasion of Ukraine
Military lapel ribbon for the Vietnam War
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2


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Image of the FS Surcouf (N N 3)
Image from the Public Domain.

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