Dwarf Fortress taught me to always import bismuthinite and cassiterite stones on embark, along with willow logs. Real history shows that tin mines were a major

Dwarf Fortress taught me to always import bismuthinite and cassiterite stones on embark, along with willow logs. Real history shows that tin mines were a major strategic asset for pre-steel civilization, and Devon and Cornwall on Britain had the oldest and deepest mines in the world, and continued working after other European sources were exhausted. Even if you know how to make steel, making types suitable for non-specialty work in significant quantities was difficult until smelting technology upgraded to the Bessemer process, and the types of available steels meant that a lot of cannons were still cast bronze. On a historical scale, it is only very recently that newer steel alloys and mass-produced aluminum has obsoleted bronze for just about everything but cymbals, certain corrosion-resistant fittings, and yellowish coinage cladding.