Missile Trident 1C4

The Trident I (C4) entered service in 1979 as a replacement for the Poseidon missile system. Development included a test launch featuring a drag-reducing aerospike on 18 January 1977. The system was designed to allow launch platforms to operate at greater distances from targets to enhance survivability. It was retired from service in 2005 following the transition to the Trident II.

The missile is a three-stage, solid-fueled submarine-launched ballistic missile. It utilizes an astro-inertial guidance system, resulting in a circular error probable (CEP) between 229 and 500 meters. The delivery system carries up to eight W76 warheads within Mark 4 reentry bodies. Each warhead has a nuclear yield of 100 kilotonnes.

The United States Navy operated the Trident I on various classes of ballistic missile submarines. The missile was retrofitted into James Madison- and Benjamin Franklin-class vessels and served as the primary armament for the initial group of Ohio-class submarines. While the Royal Navy requested the Trident I in 1980 under the Polaris Sales Agreement, the agreement was modified in 1982 to supply the Trident II instead. The system was fully withdrawn from service in 2005.