The Franklin expedition left an enigmatic collection of clues across the Canadian Arctic; while the details have taken generations to piece together, the Admiralty had the broad brush-strokes within a few years of the expedition's demise. I haven't seen the show or read the novel on which it's based, but there is a wealth of writing out there on the Franklin Expedition.

Terror and Erebus set out from the coast of Greenland in the summer of 1845 and entered the Parry Channel (the broad seaway running west of Baffin Bay, between the islands of the Canadian Arctic.) Their proposed route towards Alaska had been mapped out: only a short unexplored section remained to join the dots between Parry Channel and the navigable coast of North America. It was expected that they would spend three years in the north. Polar missions spent their summers exploring and charting the seaways, then as the sea-ice closed in at the end of the summer they'd make camp and bunker down; when the waters thawed again, they'd return to the passages of the Arctic archipelago.

When by 1847 no messages had been received from Franklin and his team, it was clear to the Admiralty that something had gone terribly wrong. They sent teams into the Arctic in summer 1848 to look for the trail.

Ross follows in Franklin's footsteps

Franklin and his men had in fact spent the winter of 1845 in the area where one of the Admiralty's teams was searching, but thick summer ice meant the rescuers returned empty-handed. Franklin made his first winter camp at Beechey Island (just off Devon Island), along their proposed Northwest Passage route. Unfortunately, the rescue mission led by Captain James Clarke Ross encountered icier seas in 1848 than when Franklin had passed through, and had to turn back about 30 miles short of Beechey Island. Later expeditions would find the remains of the camp and the graves of three sailors who'd died of respiratory illnesses during that winter stay.

Captain Ross was an distinguished polar explorer in his own right: though he couldn't penetrate far enough into the Arctic to find clues, his team did make a survey of the seaways in the area to guess where Franklin might have been able to sail. Ross noted that the passages leading south out of the Parry Channel had particularly heavily ice, indicating that they had been frozen and impassable for a number of years. This suggested that when Franklin tried to sail south towards the mainland as planned in the summer of 1846, he would have found the channels much too icy to navigate. They were thus ruled out. When the rescue mission returned to Europe, it was with the recommendation that future efforts concentrate on channels branching northwards, in case Franklin went looking for a transpolar route.

Franklin's real route

In fact, one of those southbound passages (Peel Sound) had been navigable in summer 1846. Franklin had set out from Beechey Island along his planned southward route and found it blocked by ice - but found a previously uncharted seaway also running south. Terror and Erebus sailed down Peel Sound, not knowing how unusual it was for that channel to be usable. It froze behind them and remained that way for years to come, making any future rescue by sea impossible.

Franklin did not spend the second winter of his expedition in a sheltered harbour, but with his ships trapped in the ice off King William Island, about 300 miles (500 km) south of Beechey Island. To their dismay, even with 1847's summer thaw the ice remained too heavy to free their ships and return to exploration. In keeping with standard practice, the crew ventured onto the island and left two notes under cairns, noting their position and declaring all well. The sea ice held them fast in the winter of 1847 and into the summer of 1848.

In April 1848, the crew amended one of the notes with an update: 21 men had died since the previous summer, including Sir John Franklin. It also stated that the survivors were about to leave the ships to try to get to Back River. This would mean following the western edge of King William Island southwards towards the Canadian interior.

The quest for Back River

The mouth of the recently-explored Back River lay around 200 miles (300 km) southeast of their position as the crow flies, and was rich in game. Its upper reaches were also frequented by European fur traders working for the Hudson's Bay Company. A team of crew members remained with the icebound ships while the rest of the survivors set out; they may have aimed to follow their comrades by sea if the ice relented around their ships.

The walkers broke into smaller groups for the journey. They followed the coast of King William Island in an L-shape, travelling south and then east. At least one party dragged a small boat from either Erebus or Terror in case they found open water. They hunted caribou and seals, sometimes joining forces with Inuit hunters. This was the state of affairs in summer 1848, just as Captain Ross entered Lancaster Sound far to the north to search for them, and declared that they could not possibly have gone south via Peel Sound.

On King William Island, progress appears to have been extremely slow. The crew was equipped for brief forays onto land to hunt or make scientific observations, not extended overland expeditions. Though their diets had been supplemented by hunting, supplies must have been almost entirely depleted, and studies of their remains have indicated serious mineral deficiencies that would have left the men profoundly immunocompromised. Taking what we know at face-value, the southbound party spent over a year crossing the wastes of King William Island, slowed by extreme conditions and worsening health. Shallow graves dotted along the coast indicate that dozens of men died along the way.

In the winter of 1849/50, a party of Inuit sold seal meat to a group of about 40 European sailors (with a boat) who were thin, weak, and had hard black mouths suggesting severe scurvy. When the same Inuit encountered the sailors later in the winter, only a handful were still alive and the Inuit reported they were eating their dead. Cooking pots found on King William Island (at a spot now called Erebus Bay) sadly support their observation.

Another journey down the coast

By the summer of 1850, only one group from the Franklin expedition was still definitely alive: the crew who had stayed with Erebus and Terror. Finally, having been stuck since September 1846, the weakening men managed to free the ships from the ice. They passed through Victoria Strait, which defines the west coast of King William Island, and reached Queen Maud Gulf before the seas re-froze. They had done it. The gulf had been mapped in 1839: its waves lapped the northern shore of the North American mainland, which could be followed from here all the way to Alaska and the Pacific. The route they had taken was so treacherous that future explorers would avoid it, but unknown to the wider world, Erebus and Terror had confirmed that the seaway existed.

Terror became trapped in ice again off the south coast of King William Island (today called Terror Bay). Erebus made it 50 miles further south and reached mainland North America at the Adelaide Peninsula. Erebus remained intact long enough for Inuit to go aboard in 1850 and find a dead officer in the cabin. Both sank; their wrecks are now part of a national park.

There is evidence on both sides of the Simpson Strait (which separates King William Island from North America) that the wrecks do not represent the limit of the crew's journey. Remains were found 30 miles east of Terror Bay on the King William Island side; on the mainland side, a later investigation found clothing and a medal 50 miles east of where Erebus sank. Inuit did report a small group of Europeans hunting on the Adelaide peninsula in 1850. Had these men abandoned ship in 1850, or had they been walking since 1848? We may never know.

Filling in the blanks: John Rae

As Captain Ross followed in Franklin's footsteps by sea, the Admiralty sponsored two other missions: one sailing east from Alaska, and an overland expedition with explorer Dr John Rae, who was charting the far north of Canada for Hudson's Bay Company. He found it - but not from a source that the Admiralty deemed credible.

In 1854, Rae spoke with Inuit who reported encounters with Franklin's men: specifically, that they had tried to hunt in King William Island, had traded for food, resorted to cannibalism, and starved to death. The Inuit sold Rae cutlery from Erebus and Terror bearing the monograms of officers, which he brought home as evidence of contact. His report, however, leaked to the press and caused outrage. The failure of this high-profile mission was sensational, but the lurid tale of cannibalism made the story unacceptable. Upstanding men of the Navy could not have been involved in such behaviour: Rae's Inuit interlocutors were accused of lying (at best) or of killing and eating the explorers themselves (at worst). Sir John Franklin's widow fought tooth and nail to deny Rae the reward for information.

It took decades - guided by Inuit eyewitnesses - to uncover the string of graves down the coast of King William Island and to discover the wrecks in 2014 and 2016. Those finds corroborate the Inuit version of events, and give us a fuller picture of what happened.

(continued with sources)