Key point: The German Navy still wants its submarines to be able to kill air assets to this day.
At the height of the World War II Battle of the Atlantic, Grand Adm. Karl Dönitz, mastermind of the Nazi U-Boat fleet, issued Standing War Order 483 in defiance of conventional wisdom. The “Fight Back Order” instructed German submarines transiting from French bases through the Bay of Biscay to fight off attacking aircraft on the surface rather than evade with a hasty crash dive.
This order came about because the submarines were pitted against British and American anti-submarine planes in an unprecedented arms race—one the deadly U-Boat fleet was losing.
Patrol planes had played a role in searching for and destroying submarines since World War I. However, in World War II the Nazi U-Boat fleet suffered a few losses to air attack between 1939–41. Things changed dramatically with the British development of aircraft-mounted ASV surface-search radars.
World War II-era submarines needed to surface frequently to run their air-breathing diesel engines. ASV radars—even with their short effective range of six to ten miles at the time—allowed lumbering maritime patrol planes to pick up surfaced submarines at night, when U-Boat commanders usually preferred to recharge batteries.
To illuminate targets at short range where radar proved ineffective, the British also developed the Leigh Light—a two-foot diameter twenty-two-million candle-power searchlight carried underwing.
The U-Boat wolf packs were suffering heavy losses by late 1942—but briefly technology came to their rescue with the introduction of the Metox Radar Warning Receiver, which beeped when it detected an approaching radar. Then in March 1943, the Kriegsmarine revised the Enigma encryption system it used to communicate with U-Boats, which the Allies had hacked. In March 1943, U-Boats sank 120 ships for ten losses.