After the drinking water sources were poisoned with sulfur, the city of Tortona, an ally of Milan, surrendered on condition to the besieging army of Frederick Barbarossa. The inhabitants obtained the right to leave the city center unharmed, taking with them what they could, and then the Teutons and their allies from Pavia looted and destroyed what remained. The siege lasted over six weeks: Frederick realized that the Italian municipalities, even the smallest, would give him a hard time…
