Leander-class

🇨🇱 Chile • 🇪🇨 Ecuador • 🇮🇳 India • 🇮🇩 Indonesia • 🇳🇱 Netherlands • 🇳🇿 New Zealand • 🇵🇰 Pakistan • 🇬🇧 United Kingdom

The Leander-class, or Type 12I (Improved) frigates, were developed for the Royal Navy to provide a general-purpose platform combining anti-submarine, anti-aircraft, and air direction roles. The design was based on the hull and steam turbine machinery of the preceding Type 12 Whitby-class but incorporated a more versatile layout. The class was constructed in three batches between 1959 and 1973.

The design featured a flush deck and a single-block superstructure amidships, which improved bridge visibility compared to earlier models. A hangar and flight deck were integrated into the stern to support a light anti-submarine helicopter. For nuclear, biological, and chemical defense, the ships were built without portholes and were fully air-conditioned. Propulsion was provided by two oil-fired boilers and geared steam turbines.

The class underwent several major refit programs to integrate evolving weapon systems. Initial vessels were equipped with a main gun mount and Seacat surface-to-air missiles. Batch 1 refits replaced the gun mount with the Ikara anti-submarine missile system and added an automated weapon data system. Batch 2 and Batch 3 conversions replaced the gun mount with Exocet anti-ship missiles and provided the capability to operate the Lynx helicopter. Batch 3 vessels were built with a wider beam and utilized the Seawolf surface-to-air missile system. During the 1980s, five units were fitted with passive towed array sonars for long-range submarine detection. One vessel, HMS Juno, was converted into a navigational training ship, which involved removing its armament and extending the flight deck.

Operational service included deployments during the Indonesia–Malaysia confrontation and the 1973 and 1975–1976 Cod Wars, where vessels were used for fishery protection. During the 1982 Falklands War, four members of the class participated in operations. HMS Argonaut sustained damage from air attacks in San Carlos Sound, while the Seawolf-equipped HMS Andromeda provided air defense for the carrier task group. HMS Ariadne utilized specialized electronic warfare systems during the conflict.

The Leander design was utilized by several international navies. The Royal New Zealand Navy and Chilean Navy operated the class, while licensed variants were built in Australia as the River class, in India as the Nilgiri class, and in the Netherlands as the Van Speijk class. Royal Navy units were later sold to the navies of Ecuador, Pakistan, and Indonesia. The Royal Navy decommissioned its final Leander-class ships by 1993. Retired vessels were subsequently used as targets, scrapped, or scuttled as artificial reefs in the United Kingdom and New Zealand.