Machiavelli works to achieve his secondary purpose -to inform his readers by describing the emotions of the people in a conquered republic.
Explanation:
Machiavelli believes that by perfecting the art of war , he will be able to acquire a state and be able to maintain what he has acquired.That is the primary purpose of his.
His secondary purpose is the belief that in conquered republics the emotions of the people bend towards the extreme . There is more hatred, more desire for vengeance among the people.
So its best for the king to take a marked decision that after conquering the state, the best way to maintain and keep it will be to either destroy it or stay and be a king to them and govern the state.