Association was launched at Portsmouth Dockyard in 1697 as a 90-gun second-rate ship of the line. By the time she sank, she had already survived one of the worst weather events in English history - the Great Storm of 1703, which she rode out at anchor off Harwich. Her rigging was cut to keep her from being driven onto the Galloper sandbar, and she ended up blown all the way to Gothenburg before her crew could work her home. In the years that followed she served as the flagship of Admiral Sir Cloudesley Shovell in the Mediterranean during the War of the Spanish Succession. She helped take Gibraltar on 21 July 1704, and she was in the line of battle at Toulon in the summer of 1707. By October of that year, the Toulon campaign over, Shovell was bringing his squadron home. Twenty-one ships entered the western approaches of the English Channel on the night of the 22nd. They were further north than they thought they were. Nobody on board, including the admiral, knew it.

It is tempting to tell this story as a story of an admiral, but the admiral was one of two thousand men, and most of the others have no monuments and few documented names. The Association carried about eight hundred men: ordinary seamen, idlers, gunner's mates, powder monkeys as young as twelve, marines, officers, ship's boys, the carpenter and the cook and the surgeon and his loblolly boy. The lower decks would have held men from Wapping and Plymouth and the Welsh coast and the Channel ports, men who had survived broadsides at Toulon and disease in the Mediterranean and the storm of 1703. They were going home. Many of them had wives in port towns who would wait weeks for news, then months, then learn through the slow circulation of dockyard rumour and Admiralty broadside what had happened off Scilly. Captain Loades was Rear Admiral Narborough's nephew - Shovell had married Narborough's widow - and the admiral's two stepsons, John and James Narborough, drowned next to him. Henry Trelawney was a bishop's son. But the rest were sons of carpenters, farmers, tenants, fishermen. Three other ships - HMS Eagle, HMS Romney, HMS Firebrand - struck the same chain of rocks the same night. Of the entire combined complement, almost no one survived. The dead were never counted exactly. Nearly 2000 is the best estimate that history records.

What happened was a navigation failure of the kind that haunted every captain in the age of sail. Shovell's squadron had been blown northward in stormy weather across the Bay of Biscay and into the Western Approaches. Their dead reckoning - the running tally of compass course and estimated speed that was the only way to know where you were when you couldn't see the sun or stars - placed the fleet further south, near the safe waters of the western Channel. The Scilly Isles were marked on the charts much further north than they actually are. Cloud cover meant no celestial fix had been possible for days. When the Association struck the Outer Gilstone Rock at eight o'clock at night, it was the convergence of every error in the system at once: bad charts, bad weather, no way to know longitude at sea. The popular story that a sailor warned Shovell of the danger and was hanged for it is almost certainly an apocryphal addition, generated later by people who wanted the disaster to have a villain. It did not. It had only mathematics that did not yet exist.

Latitude, in 1707, was a solved problem - you could measure the angle of the sun at noon or the pole star at night, and from that derive how far north or south you were. Longitude was the problem nobody could crack. To know how far east or west you were, you needed to know exactly what time it was at a fixed reference point - a clock that kept perfect time through months of damp, salt and ship's motion - and no such clock existed. The Scilly disaster, with its admiral and its bishop's son and its silent eight hundred, forced Parliament's hand. In 1714 the Board of the Admiralty's recommendation became the Longitude Act, which offered a reward of up to twenty thousand pounds - a fortune for the era - for any practical method of determining longitude at sea to within half a degree. The clockmaker John Harrison would spend the next forty-six years of his life building the marine chronometers that eventually won that prize. Every accurate GPS reading on a modern aircraft instrument panel descends, by a long but unbroken chain, from the moment HMS Association struck the Outer Gilstone Rock.

For two and a half centuries the wreck lay where it fell, on the Gilstone Ledge southeast of Bishop Rock, in tide-riven water that the locals knew was deadly to work. In June 1967 Engineer-Lieutenant Roy Graham of the Royal Navy returned for a second attempt with the minesweeper HMS Puttenham and twelve divers. The first attempt, the year before, had ended with his team being swept clean through the reef in white water and emerging on the other side. On the second attempt they found a cannon. On the third dive they found silver and gold coins underneath the cannon. The Association had been carrying a war chest. The volume of what was lifted - and the chaos of unregulated treasure-hunting that followed - led directly to the Protection of Wrecks Act of 1973, which now safeguards the site. In 2017 the Cornwall and Isles of Scilly Maritime Archaeology Society returned with proper survey gear and produced a 3D site plan for Historic England. There is a memorial in the church at Knowlton, near Dover, the Narborough family home, that depicts the sinking. Many of the sailors washed ashore at St Agnes are reputed to be buried under what is now the island's playing field. Children play cricket above them on summer evenings.