It all began in 1731 when Robert Jenkins, the captain of the Rebecca, had his ear sliced off by Juan de León Fandiño of the Spanish patrol boat La Isabela. Storming the British brig in the Caribbean, Fandiño accused Jenkins of smuggling sugar from Spanish colonies. He would cut King George’s ear off too, Fandiño threatened, were he to be caught stealing from Spain. Testifying before parliament in 1738, Jenkins produced the severed ear (pickled in a jar), which is why the nine years of fighting that followed became known as the War of Jenkins’ Ear.

In retaliation, the British sent a squadron of five men-of-war and a scouting sloop under the leadership of Captain George Anson, whose orders were to cross the Atlantic and go round Cape Horn, ‘taking, sinking, burning, or otherwise destroying’ enemy ships. In a secret mission, they were also to destroy a Spanish galleon – ‘the prize of all the oceans’ – loaded with Peruvian silver.

Cape Horn, at the southernmost tip of the Americas, marks the edge of the Drake Passage, the most hellish strait on Earth; but the 2,000 sailors, rounded up by press gangs or drafted from Newgate and the Chelsea Hospital for veteran soldiers, were lured by the promise of a share in the loot. For the most part, the seamen were not able-bodied but old and infirm, rheumatic, deaf, blind, lame, ‘full of the pox’, ‘the itch’ and the ‘King’s Evil’. Only a third survived the voyage.

On 18 September 1740, the convoy made its way down the Channel. The flagship, the Centurion, several decks deep with two rows of cannons on each side, was a gleaming cathedral of 17 sails with a figurehead of a bright red, 16ft wooden lion. The runt of the squadron was the Wager, an ugly, tubby East Indiaman built for cargo but rekitted as a man-of-war. Its crew of 250 were commanded, until his death from fever, by Captain Dandy Kidd. He was replaced by David Cheap, a burly Scot with a Conradian sense of heroic destiny and few inter-personal skills. Also aboard was the 16-year-old John Byron, known as ‘Foul-Weather Jack’, whose account of the voyage, The Narrative of the Honourable John Byron, was read by his grandson Lord Byron, who described in Don Juan his hero’s ‘hardships’ as ‘comparative/To those related in my grand-dad’s Narrative’.

The challenge of David Grann’s own narrative is to return to a tale that has been told so many times, initially in the conflicting accounts of the survivors, that it is has become part-legend. In summary, the winds were strong enough to break a man’s neck, the waves towered over the masts, outbreaks of typhoid and scurvy turned the crew into zombies, more time was spent throwing corpses overboard than robbing Spanish galleons, and the Wager, losing sight of the squadron, ran into rocks on the coast of Patagonia. Once a ship is wrecked, the crew are no longer paid, which made discipline hard for Cheap to maintain. Relations broke down completely after he shot dead a sailor who had been insolent, and ordered those stealing food to be whipped 600 times. After five months of his authoritarian regime, 81 of the 91 castaways rowed off to Argentina, leaving Cheap and his officers marooned without food.

The fate of the Wager and its crew was recorded not only in the narrative of John Byron, who initially joined the mutineers before returning to support Cheap, but also in the journal of John Bulkeley, a gunner on the wrecked ship, who was either the hero or the villain of the tale depending on whether you support workers or management. Nothing is known about Bulkeley’s education, but the journal he kept both on board and as a castaway proved vital in garnering public support when it was published in 1743 as A Voyage to the South-Seas, in the Years 1740-1. A wild-eyed Cheap returned to England in 1745, his body crawling like ‘an anthill’, to give his own account of the mutiny. Grann tries hard to maintain impartiality as he balances the various versions of events, but he is clearly more in sympathy with Bulkeley, who led the mutiny, than Cheap.

Sea stories were usually the work of those in command, but Bulkeley’s book, as Grann points out, was written by a ‘hard-nosed’ seadog in strong, plain maritime prose. Grann does not say how, once he was marooned on the Patagonian coast, Bulkeley found the ink needed to fill volume after volume with the misfortunes of the crew, but I’m assuming it came in vats which he saved from the sinking ship along with the barrels of flour and salted beef which the castaways lived off until they were forced to eat both Byron’s dog and the raw sealskins he had been wearing as shoes.

Meanwhile, the crew of Centurion themselves became castaways when, moored off the coast of Tinian in August 1741, a typhoon blew their ship out to sea. The ship later, like a well-trained dog, returned to its owner, who then captured the Spanish galleon Nuestra Señora de Covadonga. In an 18th-century version of the Brink’s-Mat robbery, Anson’s men discovered, beneath the floorboards of the surrendered vessel, and in the bottom of bags of cheese, the equivalent of £60 million – more treasure than had ever been seized before by a British naval commander. When the Centurion returned to Spithead on 15 June 1744, the only one of the squadron to have survived, the golden haul was paraded through the streets before being distributed among the surviving crew.

Voyage Around the World, Anson’s account of his adventures, inspired William Cowper’s sublime ballad ‘The Castaway’. But my favourite commentator on the voyage is Lawrence Millechamp, purser on the Centurion, whose journal was published as A Narrative of Commodore Anson’s voyage into the Great South Sea and Round the World Perform’d between September 1740–June 1744. Millechamp, who also painted watercolours of the natural world he encountered, never lost sight of the ‘enchantment’ of it all: armadillos were ‘the size of a large cat, their nose like a hog’s, with a thick shell… hard enough to resist a strong blow with a hammer’. Staten Island – the gateway to Cape Horn – was ‘a proper nursery for desperation’, while sea mist gave everything ‘a pleasing dreadful effect’ with the ships ‘sometimes appearing like huge ruinous castles, sometimes in their proper shapes, and sometimes like large logs of timber floating on the water’. Millechamp was living inside a romance. When the crew were temporarily marooned, ‘grief, discontent, terror and despair seemed visible in the countenances of every one of us’; when they saw in the distance the Spanish galleon loaded with treasure, ‘our ship immediately grew into a ferment’; when battle began, the cannons ‘fired so quick that it made one continued sound’.

It’s curious the way a shipwreck brings out the writer in those who would otherwise never wield a quill, and how the horror of it all is described by the survivors in terms of high romanticism. Many of those who survived the Titanic began mythologising the tragedy before their rescue ship had even docked in New York.

The triumph of the Centurion and the wreck of the Wager form the greatest sea story ever told. Little wonder the events inspired Patrick O’Brian, Herman Melville, Charles Darwin, Rousseau, Voltaire, and Montesquieu. Grann, a staff writer on the New Yorker, returns to the evidence with relish, fleshing out the characters and occasionally remembering his line of argument – that the expedition was less a triumph of superhuman endeavour than a catastrophe of British colonialism. Keen to hide the atrocities which took place under Cheap’s leadership, the court martial fudged and then buried its conclusions. The mutiny on the Wager became, as the naval historian Glyndwr Williams put it, ‘the mutiny that never was’.