How do you get your assassins to master rank in assassins creed revelations

All you have to do is level them up by sendin them on missions when you visit an assassin post, or press square (on ps3), X (on xbox 360) while at the viewing section of your assassin post to assign an assassin to a city so they'll gain xp while there, NOTE: not sure if they get xp from being assigned to a city only if you invest in xp for the city or not after it's under assassin control