Loyalty saves us from the self-advantaging compromising of important relations - such as friendship, marital and professional commitments, group memberships, and so on. But as the Aristotelians would put it, its expression requires phronesis - wisdom not to allow it to compromise other important virtues ,there is something to the ancient doctrine of the unity of the virtues. I believe that is true of all virtues, but especially of the executive virtues - such as industriousness, sincerity, conscientiousness, and courage - which may become detached from substantive goods.