French submarine Pasteur

At the start of World War II in September 1939, Pasteur was assigned to the 2nd Submarine Division in the 4th Submarine Squadron in the 1st Flotilla, a component of the Forces de haute mer (High Seas Force), based at Brest.[3][4] Her sister ships Achille, Casabianca, and Sfax made up the rest of the division.[3][4]

On either 3[3] or 14[5] September 1939, according to different sources, the four submarines of the 2nd Submarine Division as well as their sister ships Agosta and Ouessant received orders to establish a standing patrol off the coast of Spain.[5] The six submarines spent six weeks patrolling off Vigo, where part of the German merchant fleet — which the Allies suspected of serving as supply ships for German U-boats[6] — had taken refuge at the start of the war.[7] One source specifies that Pasteur, Casabianca, and Sfax rotated on patrol off Vigo beginning on 1 October 1939.[3] Before their patrols ended on 30[5] or 31[3] October 1939, according to different sources, the six French submarines had spent a combined 67 days at sea on patrol in very harsh conditions with no results.[5]

On 14 November 1939, the 2nd Submarine Division received orders to proceed to Halifex, Nova Scotia, Canada, to take part in Allied convoy operations in the Atlantic Ocean.[3] Fighting bad weather, Pasteur, Achille, Casabianca, and Sfax arrived at Halifax at 07:30 on 25 November 1939,.[3] where the British Royal Navy submarines HMS Cachalot, HMS Narwhal, HMS Porpoise, and HMS Seal joined them for convoy escort operations on 26 November 1939.[5] During the winter of 1939–1940, the submarines escorted three convoys from Halifax to the United Kingdom always in difficult weather conditions.[3][8]

Beginning on 22 March 1940, the division was based at Harwich on the North Sea coast of England. On 17 April 1940, the division moved to Dundee, Scotland, to operate in the North Sea in support of Allied forces fighting in the Norwegian campaign as German forces began their conquest of Norway. While departing Dundee for her first Norwegian patrol on 18 April 1940, Pasteur collided with Achille, suffering damage to one of her diving planes and one of her propeller shafts.[3][9] She was towed first to Cherbourg, France, and then to Brest for repairs, arriving there under tow by the tug Abeille 4 on 15 June 1940.[3]

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. Pasteur was unable to move under her own power as German forces approached Brest.[2] To prevent the Germans from capturing her, she was scuttled at Brest at 19:00 on 18 June 1940.[3][2][10][11] The Germans later refloated her wreck to clear the berth.[3]

• Fontenoy, Paul E. (2007). Submarines: An Illustrated History of Their Impact (Weapons and Warfare). Santa Barbara, California. ISBN 978-1-85367-623-9.{{cite book}}: CS1 maint: location missing publisher (link)
• Gardiner, Robert; Chesneau, Roger (1980). Conway's All the World's Fighting Ships 1922–1946. London: Conway Maritime Press. ISBN 0-85177-146-7.
• Huan, Claude (2004). Les Sous-marins français 1918–1945 (in French). Rennes: Marines Éditions. ISBN 9782915379075.
• Picard, Claude (2006). Les Sous-marins de 1 500 tonnes (in French). Rennes: Marines Éditions. ISBN 2-915379-55-6.