The German U-boat captain laughed when he saw the biplane approaching—it looked like something his grandfather might have flown.

The Day Britain Sank a U-Boat with a Biplane

When the Swordfish Proved the Admiralty Wrong in the North Sea

A WWI-era biplane that the Admiralty wanted to retire sank a German U-boat, proving old technology could still win modern wars.

The morning of July 6, 1940, broke gray and cold over the North Sea, the kind of weather that made pilots curse their assignments. Sub-Lieutenant John Ninnes sat in the open cockpit of his Fairey Swordfish, a canvas-and-wire biplane that looked like it belonged in the previous war. His observer, Lieutenant Commander James Gresham, had spotted something below—a dark shape cutting through the swells. U-26 was running on the surface, her diesel engines recharging batteries depleted from evading British destroyers.

The Swordfish—affectionately called 'Stringbags' by their crews because they could carry anything—was armed with depth charges that morning. Ninnes pushed the stick forward, diving toward the submarine at barely 100 knots. The German lookouts saw him too late. At 200 feet, he released his charges.

The explosions straddled U-26's hull with devastating precision. Water erupted around the submarine as her pressure hull cracked. Kapitänleutnant Heinz Scheringer ordered an emergency dive, but seawater was already flooding the engine room. Within minutes, the crew was abandoning ship. Forty-eight German sailors bobbed in the frigid water as U-26 slipped beneath the surface forev…

💡 The Fairey Swordfish had a maximum speed of just 139 mph—slower than most civilian cars today can drive—yet it sank more enemy shipping than any other Allied aircraft in World War II.