The footage is eerie, a plunge through a dim world of lush seaweed, the underwater forests of the treeless Arctic. Objects swim into view: a bell, a small fish, a stovepipe, the barnacled bow of the ship itself. One of the discoverers said, “We spotted two wine bottles, tables and empty shelving. Found a desk with open drawers with something in the back corner of the drawer.” This ship, the Terror, sank sometime after 1848 and was found in 2016. It’s easy to see the discovery as something far away and long ago, but there is another story to be told about the ship’s role in the scramble for the Arctic, which continues to shape the geopolitics of the world.

The Terror and its sister ship, the Erebus, set out from Greenhithe, a village on the Thames downstream from London, on May 19, 1845. The expedition was headed by John Franklin, an explorer who hoped to find the Northwest Passage, a short route between the Atlantic and the Pacific that would benefit trade and assert British dominance in the far north.

The ships were equipped with monogrammed silverware and three years’ worth of food, including half a ton of mustard, a dozen tons of sugar, 9,450 pounds of chocolate, and a mountain of canned goods, as well as a sizable library and 2,700 pounds of candles, and were piled with coal to burn.

They sailed up the west coast of Greenland. From there, they proceeded into the tangle of islands at North America’s frigid end. It was not unusual for ships to get locked into the ice over winter and then sail on after the thaw, but somehow the Terror and the Erebus never got loose. Things went wrong, and then wronger, though we don’t know much about how and why.

According to a note scrawled by two officers and placed in a metal canister buried in a cairn, Franklin died in the summer of 1847, though his body has never been found. The ships were abandoned in the spring of 1848, the note in the cairn adds, and the remnants of the crews set out on a bleak trek southward in pursuit of a last chance at survival. By that time twenty-three others had also perished. “H.M. ships Erebus and Terror were deserted on the 22nd of April, five leagues N.N.W. of this; having been beset since 12th September 1846.” The final addition reads, “And start tomorrow 26th for Back’s Fish River.”

Beginning in 1850, several expeditions were launched to search for what had become a cause célèbre. Franklin’s wife, Elizabeth, who had been ambitious for his glory, insisted for years that he might be alive and was furious when the British Navy awarded her a widow’s pension. She financed the expedition that found the note in the cairn, along with a couple of skeletons, a heavy boat on a sledge, and a pair of embroidered slippers.

In the Canadian Arctic in 1854, a fur trader and explorer named John Rae encountered an Inuit man wearing the band from what appeared to be a British Navy officer’s cap. The man told Rae that he had heard from local seal hunters that they had seen forty men dragging a boat and sledges across the ice. Native people in the region had articles from the expedition, and Rae purchased some of them — monogrammed spoons and forks, a star-shaped medal — as evidence of the explorers’ fate. In the Polar Museum in Cambridge, England, I saw four of these pieces with Franklin’s family crest on them. They suggest an unwarranted confidence about who these men were and what they were doing.

Soon after this discovery, Rae reported what he had learned from his Inuit sources:

From the mutilated state of many of the bodies and the contents of the kettles, it is evident that our wretched countrymen had been driven to the last dread alternative, as a means of sustaining life.

This was a Victorian circumlocution for cannibalism. In 1981, archaeologists discovered confirming evidence — a femur that had been hacked, other human bones scattered with the disarray of food scraps rather than the orderliness of a burial. Later research suggested that long bones were cracked to get at the marrow; this is termed end-stage cannibalism, the struggle to extract the last bits of nutrition from a corpse.