The ill-fated expedition of 1845 to find the North West Passage took the public’s imagination. This song appeared quite soon after it was clear that the ships, Erebus and Terror, and all the crew were lost. It was many years before Lady Jane finally gave up hope of finding her husband John or any survivors. Discoveries are gradually coming to light now, such as the remains of the ships, and members of the crew, perfectly preserved, buried in the snow. Wikipedia is worth a read.