Fun Facts - units and shields.

If you look in the Civ tech tree, you'll see each of the ages indicated by a different type of shield.

Dark age - Round shield

Feudal Age - Kite shield

Castle Age - Heater Shield

Imperial Age - Tilting Escutcheon

Men-at-arms use a Kite Shield.

Long Swordsmen use the Heater Shield.

Knights use a Kite Shield.

Cavaliers use the Heater Shield.

Paladins use the Tilting Escutcheon.