At 7 p.m. June 25, 1944, at the end of a 10-hour anti-submarine patrol that had taken them 400 kilometres north of Scotland’s Shetland Islands, RCAF Flight Lieutenant David Ernest Hornell and his crew of eight aboard Canso 9754 were thinking of returning to land. The weather was turning bad, with low clouds and rough seas. Should they return to Scotland, or divert to Iceland, more than 800 kilometres away? When the gunner spotted a U-boat below, the choice was taken away. Hornell attacked the submarine, despite jamming the plane’s starboard guns. Instead of diving, U-1225 opened fire, ripping holes in the starboard wing and shattering its engine, which caught fire. Confident they had done in the aircraft, the U-boat crew stopped firing, allowing Hornell to manoeuvre his cripple...

On June 16, 1903, Norwegian explorer Roald Amundsen and a crew of six left home waters in a herring boat names Gjøa to sail to Canada in search of a way to the Pacific Ocean through the Arctic Ocean across Northern Canada. He was the first to navigate the Northwest Passage through the Canadian Arctic Archipelago, reaching the Bering Strait in 1906. The feat was welcomed by merchants, traders and governments on both sides of the Atlantic Ocean. The passage could cut 7,000 kilometres off the trade route from the west to east coasts of North America via the Panama Canal. But for the next century, ice made the route unfeasible. In 2007, the passage was temporarily ice-free for the first time. Merchants began pressuring to develop the passage for routine cargo transport between Asia and...