Mercenaries
The Walls of Florence
“I say, therefore, that the arms with which a prince defends his state are either his own, or they are mercenaries, auxiliaries, or mixed. Mercenaries and auxiliaries are useless and dangerous; and if one holds his state based on these arms, he will stand neither firm nor safe; for they are disunited, ambitious and without discipline, unfaithful, valiant before friends, cowardly before enemies; they have neither the fear of God nor fidelity to men, and destruction is deferred only so long as the attack is; for in peace one is robbed by them, and in war by the enemy. The fact is, they have no other attraction or reason for keeping the field than a trifle of stipend, which is not sufficient to make them willing to die for you. They are ready enough to be your soldiers whilst you do not make war, but if war comes they take themselves off or run from the foe; which I should have little trouble to prove, for the ruin of Italy has been caused by nothing else than by resting all her hopes for many years on mercenaries, and although they formerly made some display and appeared valiant amongst themselves, yet when the foreigners came they showed what they were.”
Source: Niccolò Machiavelli (W.K. Marriott, translator), The Prince, Chapter XII
The feathers of a peacock are not an actual defensive implement, only a deterrent.
Granted that mercenaries can be more faithful than one expects, as they have reputations to protect and employment with other forces may not come so easily with their history. It is folly to rely on them too heavily still. One never knows when the money will run out.
Alas, Machiavelli is getting personal here. Mercenaries in the early modern world were very much worth the money. Machiavelli always dreamt of a republic, like that of Rome. His hatred of mercenaries is based on his politics.