You are the Yorkists in the Wars of the Roses, a medieval struggle for power in England. Some royal Houses are allied with you (as they were in the real Wars) and some against. However, loyalties may change...
The wars start when you intercept the King and the Lancastrians at St. Albans. Victory eventually centres around keeping control of the King and the Tower of London; you may gain and lose control several times in the same game.