A
Civilization advance.
Building hotter forges than they needed for bronze working, ancient smelters developed iron working, the manufacture and fabrication of a much more useful
metal. Iron ore was extremely common compared to
copper and
tin, and worked iron was harder, less brittle, and could hold a much sharper
edge. It was an ideal material for tools and weapons.
Prerequisites: Bronze Working.
Allows for: Gunpowder and
Bridge Building.