A Roman soldier stationed along the Moselle River in Trier discovered that the Germanic tribe of the area, the Treveri (who were also partly what we think of as modern day Belgians from the Ardennes region, too) had a code that they used to mark out Romans and Roman encampments to be destroyed. They carved a sign in a beech tree next to the place to be wiped out. It looked like a giant hammer. This is Thor’s hammer in Norse mythology. But it was a dire portent for the Romans. The Roman generals ignored it as just a barbaric fancy, but as they proceeded with their mapping expedition up to the Elbe River near modern day Hamburg, they were followed by agents of the head of the tribe. Suddenly one day as they were returning from this camp toward Trier which was the administrative center, they were ambushed in the dark Teutoburg Forest by these same Germans and massacred almost to a man. After 9AD the Treveri Code stopped the Roman advance into Germany.
This was the sort of legend that delighted later day Adolf Hitler who espoused German nationalism.
