what was the function of the Roman cavalry?

[Sean Manning]

Medieval war saddles were rather like 'armchairs' too. I think there is real room for debate over the relative importance of closed saddles, stirups, and training for the effectiveness of different types of cavalry. In particular, as far as I know there is no evidence that early medieval horsemen felt the stirrup was anything special.

Aryaman, I agree there is a lot of evidence of cavalry fighting hand to hand with close-order heavy infantry. Given what I know about horse behaviour, this has puzzled me somewhat. I hope to study primary sources on this in depth one day, as the mechanics and equine behaviour involved are somewhat perplexing.