Btw, I should probably drop a line or two about ponies here.

During the Cantabrian wars, the natives used ponies rather than proper horses as their primary mount. And it was not because of it's speed but rather for their stamina, resistance to the bad weather and ability to operate successfully in rugged terrain or even low vegetation.

The more southerly Iberian breeds were certainly much faster and could catch the ponies that the Cantabrians used, or even the small horses the Numidians rode when Hispanic Auxilia campaigned in Africa. The trick in both cases for the locals was to use rough terrain as a place to strike and which to retreat afterwards.

Anthony can probably also tell of stories of Irish ponies giving headaches to more heavily armed cavalry (like late Armorican cavalry, or Norman knights) by operating in wooded or boggy country.