Hired defenders switched sides the moment a better offer came along

A company that outsources its entire engineering team to a contracting firm feels efficient for years. No payroll headaches, no hiring risk, just a monthly invoice for capacity whenever it's needed. Then a competitor offers the contracting firm a bigger, longer contract, and within a quarter the company discovers its product roadmap is effectively being run by people whose loyalty was never to it in the first place.

Niccolò Machiavelli would have recognized the shape of that story immediately, even though he was writing about armies rather than engineering teams. He argued that a ruler who depends on mercenaries, soldiers hired purely for pay rather than raised from his own people, can never be secure, because such troops are, in his words, disunited, ambitious, and without loyalty beyond their wages. They'll fight for you in peacetime because there's nothing at stake, and vanish the moment war actually arrives, because dying for someone else's cause was never part of the deal.

He backs this with real cases from his own era. Francesco Sforza's father, hired by Queen Giovanna of Naples to defend her kingdom, simply walked away with his troops mid-crisis, forcing her to throw herself on the mercy of the King of Aragon instead. Francesco Sforza himself, hired by Milan to fight the Venetians, won the battle for his employers and then turned around and used the same army to seize Milan for himself. Even Carthage, in its long war with Rome, was nearly destroyed by its own hired troops, despite those troops being commanded, on paper, by Carthaginian citizens.

Auxiliaries, troops belonging entirely to someone else's command that you've simply borrowed, are if anything worse. If they lose, you lose with them. If they win, you're now at the mercy of the very power you invited in to help you. Machiavelli cites the emperor of Constantinople, who called in ten thousand Turkish soldiers to help against a threat in Greece, only to have them refuse to leave once the danger passed, which is how Greece's long servitude to outside rule began.

His conclusion isn't subtle: without an army made up of your own people, citizens, subjects, dependents, no position is ever truly secure, because it rests entirely on the goodwill of forces whose interests were never actually yours.

Start by being honest about which parts of what you do are genuinely core, the things you cannot afford to have controlled by people whose loyalty was never to you. Wherever possible, build that capability with your own people, even if it costs more and takes longer than renting it would. If you do have to lean on outside help for now, treat it explicitly as temporary, and have a real plan for the point where you replace it with something you actually own. And keep half an eye on who else is bidding for the loyalty of whatever you're borrowing, because outside strength answers to whoever pays best, and that was never guaranteed to be you.