History of submarines few years before the US, and paralleled subsequent US development in this area. In the 1950s, nuclear power partially replaced diesel-electric propulsion. The sailing of the first nuclear-powered submarine, the USN ""Nautilus"" in 1955 was soon followed by similar British, French and Russian boats. Equipment was also developed to extract oxygen from sea water. These two innovations, together with inertial navigation systems, gave submarines the ability to remain submerged for weeks or months, and enabled previously impossible voyages such as the crossing of the North Pole beneath the Arctic ice cap by the USS "Nautilus" in 1958. Most of the
French submarine Espadon (S637) front of her sail. On 13 August 1963 a fire in the torpedo room wounded and intoxicated four sailors, one of whom later died of his wounds. In May 1964, "Espadon" and "Marsouin" steamed under sea ice in the Norwegian Sea as far as 70° north. "Espadon" undertook significant modifications from 1966 to 1968, notably upgrading the boat's sonar, sail and rudders. "Espadon" has been a museum ship at the "ville-port" of Saint-Nazaire in the German-built submarine base since 1987. French submarine Espadon (S637) Espadon was a "Narval"-class submarine of the French Navy. Along with sister boat "Marsouin", the boat