Answer
Francis Crozier was John Irving's superior on HMS Terror. Crozier was a British naval officer and explorer who served as the second-in-command of the Franklin Expedition, which set out in 1845 to find the Northwest Passage. After the expedition's ships, HMS Erebus and HMS Terror, became trapped in ice, Crozier and his crew abandoned the ships and attempted to reach safety on foot. They all perished in the Arctic wilderness.