Île Longue (Enez-Hir)

Île Longue is the French Navy's base for the ballistic missile submarine force, situated on a peninsula of the roadstead of Brest, attached to the Crozon peninsula in the commune of Crozon, Finistère, Brittany. It is the command centre for France's ballistic missile submarines and is among the most closely guarded military sites in the country.

The base homeports the nuclear-powered ballistic missile submarines (sous-marins nucléaires lanceurs d'engins, SNLE) of the Force océanique stratégique, which has operated from the site since 1972. Île Longue is responsible for the maintenance of the submarines and for the storage of their nuclear components, including warheads and fuel elements. Chemical pyrotechnics for the missiles and conventional warheads are held at Guenvénez, 4 km away, where the Missile Storage and Maintenance Area assembles the missiles.

The installation is divided into three colour-coded zones. Zone Blue holds security installations and personnel, including the fire service and the Fusiliers Marins responsible for ground defence of the site, together with offices and catering. Zone Red contains the pyrotechnics and the bunkers holding nuclear warheads. Zone Yellow covers the harbour and submarine installations, including roofed docks 200 m long; a 170 m bunker between them is used for loading and unloading nuclear materials. The site also includes vertical missile silos and engineering and accommodation buildings. Access is by a causeway across the former isthmus, widened and raised above high water during construction and used as a vehicle park. Work carried out since 2006 has adapted the base to the M51 submarine-launched ballistic missile.

Île Longue was selected in 1965 by President Charles de Gaulle as the shore base for the sea-based component of the Force de frappe, being close to a large harbour yet sufficiently remote and readily defended. Construction ran from 1967 to 1972 and reshaped the peninsula, which gained 30 hectares of made ground alongside the new docks, silos and support buildings. The base was declared operational in 1972, when the submarine Redoutable sailed on her first patrol.