The rules being used at Salute are an in-development version of Dux Britanniarum from TooFatLardies.
Dux Britanniarum, written by Richard Clarke, is a campaign-driven game where the British defend their land and their Roman heritage against Pagan Saxon raiders determined to carve out their own kingdom. Although set in the early Dark Ages, we found that the rules work just as well for the earlier conflict between Romans and Celtic warriors.
Dux Britanniarum, due out this summer, builds on the game mechanics introduced in Sharpe Practice and developed in the Lardies other excellent large-scale skirmish rules Terrible Sharp Sword and Through the Mud & Blood. Players of Sharpe Practice will find a lot that is familiar, but Dux Britanniarum takes the card-driven mechanics of the earlier games to a whole new level.