Machiavelli views auxiliaries, troops loaned by another ruler, as even more destructive than mercenaries. While mercenaries are only self-interested, auxiliaries are actually loyal to someone else, namely a rival prince who may use them to conquer you. Using forces that belong to someone else puts you in that person's power.
Returning once again to his theme that the only real strength is self-sufficiency, Machiavelli remarks that it is better to lose with one's own troops than to win with the strength of others, because that victory belongs to them. Unless a prince can field an army of his own citizens or subjects, he has no real power. Virtù, a prince's own strength, is always preferable to relying on luck or the favor of others.
