Because Spanish guns were useless without gunpowder, an expedition collected sulfur from Popocatépetl's caldera as a key gunpowder ingredient.

“in the innovations they need sulfur for their gunpowder they have guns useless without gunpowder so an expedition goes into the mountains to the volcano popocatepetl and they dangle with ropes inside the caldera of the volcano scooping out the sulfur they need as the critical ingredient for their gunpowder another one”