Lordclane
Chieftain
A few ideas....
The stirrup - made cavalry more effective and horse archers possible.
The keel - made ocean-going ships possible. I note that the Maoris, Micronesians and Vikings all had ocean-going ships well before Civ4's technology trees would allow them.
General staff - introduced around the time of Napoleon, made it possible to effectively coordinate multiple armies. In game terms, you might increase all ground movement by +1.
Telegraph/Telephone - made it possible to coordinate business and government across geographic distances more effectively. In game terms, it would reduce penalties for distant cities.
The stirrup - made cavalry more effective and horse archers possible.
The keel - made ocean-going ships possible. I note that the Maoris, Micronesians and Vikings all had ocean-going ships well before Civ4's technology trees would allow them.
General staff - introduced around the time of Napoleon, made it possible to effectively coordinate multiple armies. In game terms, you might increase all ground movement by +1.
Telegraph/Telephone - made it possible to coordinate business and government across geographic distances more effectively. In game terms, it would reduce penalties for distant cities.