Until the fall of 1916, the Adriatic Sea was the private domain of the Austro-Hungarian Fleet. But then, Allied submarines crept in to menace their shipping, and the Central Powers were powerless against them. In an urgent move, the fleet set up a seaplane station at Kumbor, Austria.

On September 15, 1916, a submarine was spotted, and two seaplanes took off from Kumbor on the hunt. Sub-lieutenant Walter Zelezny piloted one Austrian Lohner Flying Boat, Lieutenant Konjovic, his commander, the other. Zelezny flew to the area where the French Laubeuf-type sub, the Foucault, was last sighted. He dove and dropped his depth charges, both of which exploded 20 feet to starboard of the Foucault—one at the stern, one at the bow. The sub was gone. He was sure he had missed, but he was dead wrong.

Water gushed into the Foucault. She sank quickly into the deep. The depth gauge showed 250 feet, and the men waited to die. After 30 endless minutes, the hand on the gauge moved. The electric pumps had lifted the Foucault out of her watery crypt! As the submarine surfaced, 29 men stood on the deck of the Foucault, alive but lost in the vastness of the sea. Zelezny was able to sink the sub with a small bomb, but amazingly, he and Konjovic landed in the midst of the sailors who’d been swept overboard. They pulled the wet, cold crew onto the wings, floats, and hull of their seaplanes, saving every single man!

Zelezny received many congratulations. His father wrote, “I am very pleased with your success, especially as no mother will cry following the sinking of the French submarine and your rescue of all the crew.”