HMS Dreadnought, Britain's first nuclear powered submarine, was commissioned in 1963 and opened a new chapter in the history of the Royal Navy. In 1955 the United States Navy had completed USS Nautilus, the world's first nuclear powered submarine. It soon became clear that this was a revolution in submarine design, not merely a more convenient form of propulsion. Using her superior speed and endurance compared with conventionally powered submarines, Nautilus ran rings round British anti-submarine forces on exercise and the Admiralty decided to build nuclear powered submarines.

Excellent relations between Admiral Lord Louis Mountbatten, the First Sea Lord, and Rear Admiral Rickover, in charge of the American nuclear submarine programme, helped to obtain considerable American help for the building of Dreadnought. Most important was the purchase of a nuclear reactor system.

Dreadnought's main role was to detect and destroy enemy submarines. Her endurance and versatility were shown in 1967 when she travelled from Rosyth to Singapore and back and in 1971 she became the first British submarine to surface at the North Pole. In 1973 Dreadnought took part in the navy's first annual Group Deployment, when a group of warships and auxiliaries would undertake a long deployment to maintain fighting efficiency and 'show the flag' around the world. Together with the frigates Alacrity and Phoebe, Dreadnought was deployed to the South Atlantic in 1977 to deter possible Argentine aggression against the Falkland Islands. Due to machinery damage and the limited refit facilities then available for SSNs, Dreadnought was withdrawn from service in 1980.

The effectiveness of nuclear powered submarines was clearly demonstrated in the Falklands War . On 2 May 1982 HMS Conqueror torpedoed the Argentine cruiser the General Belgrano. With no means of detecting the Conqueror and fellow SSNs HMS Spartan and HMS Splendid the entire Argentine navy withdrew to coastal waters for the remainder of the conflict.