Strictly speaking, there was only one battle described in the entire book, which was the last stand on Stable Hill. It's implied that there was some kind of conflict at Cair Paravel, though it probably could be descibed as a skirmish at best (probably "massacre" would be more accurate). Roonwit never got a chance to command an army, even the small one Tirian told him to bring. Farsight saw him with a Calormene arrow in his side, though the story never mentions how he got it. I'd always thought it was a "sniper" of some sort, but he may have strayed close enough to Cair to get caught on the edge of the strife.