The Italian submarine Luigi Torelli raced across the Atlantic’s surface, her crew confident in the night’s protection. Enemy escorts were blind in these waters. In 1943, surfaced submarines were still invisible to radar at close range. The submarine owned the night.Out of nowhere, a searing white flash sundered the starless sky with the power of 750,000 headlights.The crew on watch froze, stunned, as the Atlantic night gave way to a blinding day. A white glare swept across the deck, piercing the waves and scalding their vision. It wa s as if the ocean itself had caught fire.The captain’s eyes adjusted just in time to make out something tumbling from within the blinding glare. As soon as the dark shadows touched the deck, fireballs erupted, his ship convulsed. Suddenly, the most effective weapon against an Axis submarine was light.