Wager was a converted East Indiaman, bought by the Admiralty in 1739 to join Commodore George Anson's squadron raiding Spanish ports on the Pacific coast of South America. She carried the expedition's siege guns and ammunition - which made her indispensable, and made her captain unwilling to abandon his orders. The voyage was cursed before it began. Among the crew were 470 invalids and pensioners pulled from Chelsea Hospital, elderly and infirm men sent to fill out the ranks; most were among the first to die. Scurvy did the rest, rotting gums and reopening old wounds as the squadron beat westward into the worst seas on the planet. When a savage night separated Wager from the others, the squadron assumed her lost and sailed on.

Alone and barely crewed, Wager argued with herself over where to turn north. Her captain, David Cheap - a brave and capable seaman, but rigid and quick to rage, and commanding a large ship for the first time - held his course toward the mainland. The gunner, John Bulkeley, the most skilled sailor aboard, pleaded with him to bear away from the lee shore. Bulkeley was right. On 13 May the carpenter glimpsed land to the west that went unreported; the next afternoon it was unmistakable, and as the crew scrambled to claw offshore, Cheap fell and dislocated his shoulder. That night the ship struck and struck again. Water flooded the lower decks, drowning dozens of the sick where they lay. Some men broke into the rum and drank themselves into a violent stupor as the hull bilged open beneath them.

On the island, authority dissolved along with the ship. The survivors were freezing, starving, and bitterly divided, many blaming Cheap for everything. Tensions broke when the captain, hearing a commotion outside his tent, emerged in a fury and shot a young midshipman named Henry Cozens in the face at point-blank range. Cozens took ten agonizing days to die. The killing hardened the men against Cheap. Bulkeley proposed a desperate plan: lengthen the longboat into a schooner and sail home the long way, through the Strait of Magellan to Brazil. Cheap refused again and again. So on 9 October, armed seamen entered his hut, bound him, and declared him their prisoner - to be taken to England, they said, to answer for Cozens's murder. The captain was stunned. He had not understood how far things had gone.

On 13 October 1741, the schooner Speedwell sailed with most of the men crammed aboard. Cheap chose to stay behind. The voyage that followed was a slow horror of starvation: men died in the open boat day after day, some begged to be put ashore on the desolate coast rather than continue, and Bulkeley twice abandoned groups of sailors on barren shores to a seemingly certain death. After more than 2,000 miles and fifteen weeks, only 30 of the 81 who had set out reached Rio Grande, near death. Cheap's path was stranger still. His marooned party tried to sail north, failed, and limped back to the island in despair. There a band of Chono people, a seagoing Indigenous nation of the southern channels, led by a man named Martin Olleta, found the castaways and agreed to guide them to a Spanish settlement in exchange for their boat and iron, a metal precious in this hard country. The four-month journey killed all but four. Cheap and the midshipman John Byron were among the survivors.

The astonishing twist was that nearly everyone presumed dead came back to contradict everyone else. Bulkeley reached England in 1743 and published his journal; some thought he should hang. Cheap arrived two years later, with his own version. Men abandoned on hostile coasts clawed their way home to confront the comrades who had left them. When the court-martial finally convened in 1746, the Admiralty quietly narrowed its scope to the loss of the ship alone, avoiding the explosive question of mutiny. Nearly all were acquitted. The mutineers had argued that since their wages stopped the day the ship sank, naval law no longer bound them - a loophole Anson moved to close by act of Parliament in 1747. Byron rose to vice admiral and fathered a line that produced his grandson, the poet Lord Byron, who would draw on these horrors in his darkest verse.