At the declaration of World War II in September 1939, French submarine forces aligned 77 vessels out of which 47 were launched in advantage ten years prior and 19 submarines in due course of construction, a submarine supply vessel, the "Jules Verne" was in service since April 1932. The French Navy counted 9 units of 1200 tons-class, 29 units of the 1500 tons-class ( and "Phénix", were lost accidentally in 1932 and 1939); 38 units of the 600 tons-class ( was lost in 1928 and "Nymphe" was condemned in 1938) out of which 6 mine laying submarines of the and grand cruiser "Surcouf", which displaced 3300 tons in surface, being the largest submarine in the world during the époque. Besides grand cruiser "Sucouf", the German U-boat of the Kriegsmarine were technically superior as an entire.