Introduction
The 1st Submarine Squadron (SM1) is a Royal Navy submarine squadron responsible for all operational British ballistic missile submarines (SSBNs). The squadron is based at Her Majesty’s Naval Base (HMNB) Clyde, located on Gare Loch, Strathclyde, Scotland.

Established on 1 October 1993, SM1 formed from the merger of the 3rd Submarine Squadron (SM3) and the 10th Submarine Squadron (SM10). Captain McLees, previously commanding SM3, became the first captain of the newly unified squadron.
Currently, SM1 operates four Vanguard-class nuclear-powered SSBNs, each armed with Trident II D5 submarine-launched ballistic missiles (SLBMs). These submarines routinely transit between Faslane and Kings Bay, Georgia, where they embark and disembark their Trident missiles.

When not deployed aboard submarines, the nuclear warheads are securely stored at the Royal Naval Armament Depot (RNAD) Coulport. The Coulport facility extends approximately one and a half miles along the eastern shore of Loch Long and lies approximately 11 miles by water, or seven miles by land, from Faslane.
Additionally, SM1 shares HMNB Clyde with the 2nd Submarine Squadron (SM2), composed of attack submarines.
Ships of the unit
One submarine of the Vanguard class is always on patrol, providing the UK’s nuclear deterrence, while another is typically undergoing refit.

Each submarine is crewed by two alternating teams, known as Port and Starboard, allowing one crew to patrol while the other engages in training or leave.
Commanders
List of Squadron Commanders (partial):
- Captain J. McLees
- Captain J.W.R. Harris
Further Reading
Bibliography
- Hall, K. (2018). Polaris: The History of the UK’s Submarine Force. United Kingdom: History Press.
- Norris, R. S., Burrows, A. S., Cochran, T. B., Fieldhouse, R. W. (1994). Nuclear Weapons Databook, Volume V: British, French, And Chinese Nuclear Weapons. United Kingdom: Avalon Publishing.