Steel allows the building of battleships, one of the most fearsome units in Civilization.
It is a prerequisite of automobile.
| Prerequisite advances:|
| Steel (Civ1)|
| Needed for further advances:|
With the Industrial Revolution came new needs for metals, both as construction materials and for fabrication into products. The rise of Railroads especially spurred research in Metallurgy for a metal that could be fashioned into cheap, strong rails and bridges. Eventually, the secret of Steel was discovered, and it was found to be a nearly perfect construction material. However, it could not be made cheaply until Industrialization brought the resources and machines together at one time. In turn, Steel led to great changes in the world, including enormous skyscrapers, armored warships, and the Automobile.