Exmouth had not been designed for what killed her. She was a destroyer flotilla leader - larger than a standard destroyer, with extra accommodation for a flotilla commander and his staff, ordered under the 1931 Naval Programme and laid down at Portsmouth Dockyard on 15 March 1933. She displaced 1,495 long tons standard, ran 343 feet from stem to stern, and made 36 knots flat out on two Parsons geared steam turbines. Five 4.7-inch guns. Eight 21-inch torpedo tubes. Twin Vickers half-inch quadruple mounts for anti-aircraft. She was launched on 30 January 1934 and commissioned for service on 9 November of the same year, becoming leader of the 5th Destroyer Flotilla of the Home Fleet.

Exmouth's career through the 1930s tracked the slow gathering of the European storm. From August 1935 to March 1936 the Admiralty attached her flotilla to the Mediterranean Fleet because of the Abyssinia Crisis - Italy's invasion of Ethiopia threatening to draw the Royal Navy in. She was refitted in Alexandria over the winter of 1935-36. Then came the Spanish Civil War. From 1936 to 1939 she spent long stretches in Spanish waters enforcing the arms blockade that Britain and France imposed on both sides of the conflict under the Non-Intervention Committee. Two annual refits at Portsmouth broke up the patrols. By March 1939 she was back in Britain. By August of that year - days before war broke out - she had been recommissioned as leader of the 12th Destroyer Flotilla.

When war began in September 1939 Exmouth was with the Home Fleet. In December the Admiralty transferred her to the Western Approaches Command - the great choke-point west of Ireland where the Atlantic convoys arrived - to escort merchant traffic and run anti-submarine patrols. In January 1940 they moved her again, this time to Rosyth on the Firth of Forth, to do the same work in the North Sea. The northern coastal convoys ran past the Caithness coast, through the Pentland Firth or the Moray Firth, exposed to U-boats that increasingly worked these northern waters. On the evening of 20 January 1940 Exmouth was in the Moray Firth escorting the steamer Cyprian Prince. By the small hours of 21 January she was gone.

U-22, a Type IIB coastal submarine commanded by Karl-Heinrich Jenisch, had been hunting in the Moray Firth for several days. At approximately 04:50 on 21 January she fired her torpedoes. Exmouth was hit twice in heavy seas. She broke apart and sank rapidly somewhere off the north Caithness coast. There were no survivors. One hundred and ninety men died - the entire ship's company, including her captain. Bodies came ashore over the following weeks. Most of those recovered were buried at the cemetery at Wick, the small harbour town that became the last care given to a great many of them. The Cyprian Prince, the merchant ship Exmouth had been protecting, reached Kirkwall safely.

The wreck of HMS Exmouth was not located for sixty-one years. In July 2001 an independent diving expedition found her in the Moray Firth and Historic Scotland verified the identification. She lies in deep water, broken but recognisable. Under the Protection of Military Remains Act 1986 the wreck is now designated a Protected Place: a war grave, with no diving or disturbance permitted. In 2013 the Navy News covered the unveiling of a plaque to her crew. The 190 names are kept by veterans' organisations and by an HMS Exmouth (1940) public group that still receives messages from descendants. The Caithness graves at Wick - the men they recovered, in the storm-cleaned days of late January 1940 - remain visited and tended.