The Royal Navy has officially closed a defining chapter in its submarine history with the decommissioning of HMS Triumph, the last of the Trafalgar-class hunter-killer submarines.

For more than four decades, the seven submarines were at the forefront of underwater warfare, first as Cold War warriors, and later in modern times. The decommissioning event marks the end of more than 40 years of service by the formidable “T-boats.”

Crews of the last two T-boats in service, Talent and Triumph, held Divisions at HMS Drake in Devonport, with former Trafalgar crews invited to join them.

According to the Royal Navy, collectively, T-boats have served for more than 200 years, with Triumph completing the longest career of the seven submarines: 34 years. The vessels were built to meet the demands of the Cold War, providing protection for the UK’s strategic nuclear deterrent by keeping hostile submarines away.

Much of HMS Triumph’s career falls under that banner, but it has launched Tomahawk missiles on several occasions, firstly at Taliban targets in Afghanistan in the wake of the 9/11 attacks in 2001 and, a decade later, against Colonel Gaddafi’s forces during the uprising in Libya.

Since 2009, when the first of the seven successor Astute-class submarines arrived on the scene, the boats of the Trafalgar class have been gradually phased out.

HMS Agamemnon, which is almost complete in Barrow, will replace HMS Talent, while Triumph’s duties will ultimately be taken up by the final A-boat, HMS Achilles, later this decade.

HMS Agamemnon was formally launched in October 2024.