The Danger of Borrowed Armies—And Why You Must Build Your Own — The Prince

Machiavelli turns from mercenaries to auxiliaries, the allied troops a prince calls in for aid. They may be good in themselves, but for the prince who borrows them they are always disadvantageous: if you lose, you are undone; if you win, you are their captive.

Pope Julius II learned this when, after Ferrara exposed the weakness of his mercenaries, he threw himself into Ferdinand of Spain's arms. Fortune alone saved him from the usual result: his auxiliaries were routed at Ravenna, then the Swiss drove out the conquerors, so he became prisoner to neither enemy nor ally. The Florentines, unarmed, sent ten thousand Frenchmen against Pisa and ran greater danger than in their other troubles. The Emperor of Constantinople sent ten thousand Turks into Greece, who refused to leave when the war ended, beginning Greece's servitude to infidels.

Auxiliaries are more hazardous than mercenaries because they are united and obey a foreign master. With mercenaries, cowardice is the danger; with auxiliaries, valour is, because they can win and then own you. The wise prince avoids both and would rather lose with his own arms than conquer with another's.

Cesare Borgia shows the progression: French auxiliaries took Imola and Forli, then Orsini and Vitelli mercenaries, then his own men, on whose fidelity his reputation kept rising. Hiero of Syracuse slaughtered useless condottieri and fought with native forces. David rejected Saul's armor because another man's arms fall off, weigh you down, or bind you.

Charles VII built France's own infantry and men-at-arms; Louis XI destroyed the infantry and leaned on the Swiss, leaving France mixed, stronger than mercenaries or auxiliaries alone but far weaker than own forces. Machiavelli closes where Rome began to fall by enlisting the Goths: no principality is secure without forces of its own composed of subjects, citizens, or dependents.