In the Nibelungenlied, the medieval epic written around 1200, the hero Siegfried bathed in dragon’s blood and cannot be wounded, except for one spot on his back where a linden leaf lay. His enemy Hagen gets his wife Kriemhild to tell him where the spot is. He asks her to mark it on Siegfried’s clothing with a small cross, so that he can protect him in battle. With that knowledge Hagen kills Siegfried from behind with his own spear.