Le Triomphant-class

The Triomphant class, designated Sous-Marin Nucléaire Lanceur d’Engins de Nouvelle Génération (SNLE-NG), consists of four ballistic missile submarines operated by the French Navy. Developed by DCNS, the class succeeded the Redoutable class to provide the ocean-based component of the French nuclear deterrent, the Force océanique stratégique. Construction occurred between 1986 and 2010, with the lead boat entering service in 1997.

The propulsion system centers on a K15 pressurized water reactor and a turboreductor pump-to-shaft system. Electronic and sensor systems include DMUX 80, DUUX 5, and DSUV 61B sonar arrays, alongside a SET tactical operational system. Compared to the preceding class, these vessels feature reduced detectable noise and increased sonar sensitivity. The class is equipped with launch tubes for ballistic missiles and torpedo tubes for F17 torpedoes and Exocet SM39 anti-ship missiles. While the first three units originally carried M45 missiles, the class was designed for the M51 missile. All units were subsequently retrofitted to the M51 standard, and the M51.3 variant entered operational service in late 2025.

Based at Île Longue in Brittany, the French Navy maintains four active units: Le Triomphant, Le Téméraire, Le Vigilant, and Le Terrible. The operational cycle is intended to ensure two submarines are on patrol. In February 2009, Le Triomphant collided with the Royal Navy submarine HMS Vanguard while submerged. Le Triomphant sustained damage to its bow sonar dome but returned to its home port under its own power. The decommissioning of the final Redoutable-class vessel in 2008 left the Triomphant class as the sole ballistic missile submarine class in French service until the planned introduction of the SNLE 3G.