@juergen_hubert many of these sorts of wartime magic tales date back to the Thirty Years War and earlier, but in the end they all boil down to "We didn't kill the soldier, honest! It was a curse!"

The Fränkische Schweiz probably has tales like this, but there the protagonists are most likely Raubritter (bandit knights), due to the high density of castles, valleys and caves to hide in.

@fnordius

For the Fränkische Schweiz I can recommend this book, which was basically my introduction to German folk tales as a whole.

And there was a tale about a knight of Aufseß who made himself bulletproof.

Band 5 - Sagen, Legenden und Geschichten der Fränkischen Schweiz | Fränkische Schweiz Verein

(fsv-ev.de)