"The Eternal Alliance" is a continuation of the novel "The Rally Call", the second book in the "Lost Regiment" series, which has been considered by critics to be one of the best examples of fantasy adventure literature published in recent years. Northern Army Colonel Andrew Keene and his soldiers were the first people transported through space and time to an alien planet. The democratic principles of the Americans come into conflict with the customs of medieval Rus', the peculiar morals of slave-owning Rome and the cruel laws of cannibal nomads dictating their will to other peoples. People were considered in this world as cattle, suitable only for slaughter. Having entered the fight against a horde armed with spears, swords and bows, Keene's army freed the Russians from the oppression of the nomads, but when the Carthaginians attacked the Roman Empire, the situation became sharply more complicated.