While the Second World War rages in Europe, Canada, and the (still officially neutral) United States became embroiled in a diplomatic stand-off in the North Atlantic. If ceded to German hands, Greenland could instead act as a refuelling station for U-Boats preying on that traffic. The cryolite mine at Ivigtut, Greenland, photographed in 1937. As Peter Harmsen argues in his (unexpectedly timely) 2024 book, Fury and Ice: Greenland, the United States, and Germany in World War II, the strategic importance of Greenland and its cryolite mine was initially overlooked by Allied statesmen and military planners. On the morning of 9 April, a cable from the Danish government alerted Greenland officials that the Germans had crossed the border.