Why Fortresses Are Usually a Trap—And Where Real Security Actually Comes From — The Prince

Machiavelli lists the tricks princes use to hold a state: disarm subjects, keep towns split by faction, foster enmities, win over early distrust, build fortresses, or tear them down. He will not give one rule for every state, but he can reason about each tool.

New princes never disarm their people; they arm them. Weapons turn distrusted men loyal and give you adherents instead of mercenaries. Disarming signals cowardice or disloyalty and breeds hatred. When you add a province, disarm its men except your early supporters, then soften them over time and keep armed strength near your old capital. Factions are worse than useless today: divided cities invite the enemy, as Venice learned after Vaila when one party seized power. Fortune also raises enemies so a new prince can climb on them; some even craft animosity to crush for renown.

Men who were hostile at the start, if they need your help to survive, often serve with fierce loyalty because they must cancel your bad opinion by deeds. Pandolfo Petrucci of Siena ruled through former distrusts. Beware secret favours from the discontented: they are harder to keep than former loyalists of the old regime who became your enemies.

Fortresses help or hurt by circumstance. Build them if you fear the people more than foreigners; skip them if the reverse. Francesco Sforza's Milan castle has done more harm to his house than any disorder. The best fortress is not being hated, because walls will not save a prince the people want gone; foreigners will assist a risen populace. Catherine Sforza, Countess of Forli, held out once after her husband's murder, but when Cesare Borgia came with the people against her, the fortresses failed. Machiavelli praises the builder and the demolisher alike and blames only the prince who trusts walls while letting hatred grow.