On 24 May 1847, Sir John Franklin’s 3^rd expedition reported “All well” but less than a year later, on 22 April 1848, the 129 sailors who had set out from Britain on Erebus and Terror had been reduced to 105 survivors departing their frozen ships in a desperate attempt to escape the Arctic. Since 2008, archaeological research has located the shipwrecks and acquired considerable new information concerning those survivors' escape attempt, including the fact that at least 24 were already so unhealthy that they would perish just 108 kilometers from the ships. This new evidence heightens the contrast with other comparable contemporary Arctic expeditions, some of which stayed in the Arctic considerably longer, and all of which experienced mortality rates consistent with those in the Royal Navy worldwide. This paper explores the difference that caused so many of Franklin’s crew to die during their final months on board the ships and in the initial stages of the escape attempt. Far from being a mystery, the ultimate cause of the catastrophe appears to have been wintering in the ice pack. This precluded the Erebus and Terror crews from the hunting and fishing that sustained all other expeditions.