In 1845, a British expedition led by Sir John Franklin set off to find the so-called

Northwest Passage, a sea route linking the Atlantic and the Pacific via the Canadian Arctic.

People have been looking for the Northwest Passage since the 16th century by seeing either

how far west they could get from the Atlantic or how far east they could get from the Pacific.

This was like a holy grail for sea explorers.

Given how hard it was to find, the Northwest Passage was probably not going to be much

use for shipping, even if it did exist.

So instead, it became a sort of mythical prize that generations of explorers set out to find

for its own sake, like climbing a mountain.

Franklin's expedition had the full backing of the British Empire, which at that point was at its height.

He was a naval officer who'd been involved with previous attempts to find the

Northwest Passage, and he'd lobbied hard to get the job of leading this new expedition,

with two large ships, actually decommissioned war ships, and 129 men.

The government-funded Franklin expedition travelled in style.

The ships were luxurious by the standards of previous polar missions with heating and huge

stores of preserved food.

They also had cattle, sheep, pigs and hens to provide food in the initial stages of the journey.

Each ship had a library with a thousand books,

and there were three on-board pets, a cat, a dog, and a monkey. But after setting off into

the Canadian Arctic, the entire expedition just vanished without trace.

In the years that followed, there were more than 30 attempts to find and rescue Franklin and his crew.

The British government offered a 20,000 pound reward, a fortune at the time, to anyone who could

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