Flash and Thunder: The D-Day Password
Karl Mautner answered “Thunder.” His pronunciation left the soldiers listening in doubt.
When Karl F. Mautner answered the challenge “Flash” with “Thunder,” he heard rifles being readied.
He had landed in a field in Normandy, with cows around him and no other men in sight. Unsure of his position, he started walking. When American soldiers challenged him, he knew the exchange: “Flash” called for “Thunder.”
The difficulty was how he said it. In his later account, Mautner remembered that the men did not like his pronunciation. He had given the reply they expected, but they were still unsure who he was.
What “Flash” and “Thunder” meant
The D-Day password was a challenge and response. One soldier supplied the challenge, “Flash”; the person challenged was expected to answer “Thunder.” The exchange let soldiers test an unfamiliar voice before approaching.
The words had been passed on before the invasion. In the mission preparations recorded by Col. Joseph Harkiewicz, combat crews received maps, escape kits and French money, then the password among their final instructions. The crews learned it alongside the other instructions for the operation.
The listener still had to decide whether to trust the person speaking.
Why Mautner’s accent mattered
Mautner had been born in Vienna and served in the U.S. Army. His pronunciation of “Thunder” attracted suspicion from the Americans who challenged him.
The encounter ended when one of the men recognized him.
He joined a small group heading toward Sainte-Mère-Église, where he was supposed to rendezvous with his unit.
Clickers and spoken passwords
The clicker associated with the 101st Airborne used a pattern of sounds rather than a spoken password. ACME describes one click as the challenge and two as the friendly reply. The signal depended on a shared convention, just as the words did.
Mautner recalled both the clickers and the spoken password in his account of the landing.
The story of the D-Day cricket follows the mechanical signal. Mautner's own night continued beyond the encounter, toward a meeting place he still had to reach.
His expected rendezvous time had been four in the morning. He remembered arriving at about eleven.