Philosophia
Chieftain
Sorry, about being a smartass here, but in history cavalry was divided in light (scout, kill fleeing enemies/archer) and heavy (shock troops to ride right into an enemy formation).
And heavy cavalry was very effective. The reason why I am adding this here is that I live in Switzerland, where they actually invented the pikemen (which was later adopted by the German Landsknechts, although the used a lot of two-handed swords thats why their icon is a sworn, rather than a pike) in the early Renaissance. In contrast to Civ this was actually after knights have been dominating battlefields for centuries.
No, don't worry about it at all. I rather be corrected than to go on thinking something wrong. I don't know much about military history, let alone cavalry and that's just what I got from reading the wikipedia page on it.