The horns screamed for battle, and from all sides, men responded. On a day two thousand years ago, in a country we now call France, horses rear, throwing centurions off their backs. The Romans crouch and run away like scared dogs, their red cloaks flailing behind them. Shrieking to match the horns, tribal warriors burst from the bushes to give chase. Emyn stands in a river that seems shallow and still as death--then the warriors run past, holding their swords and axes high. The screams and horns stopped. Emyn looked around. The sun shone on the curious faces of the king and his guests. As...