Unlike hereditary principalities, new principalities present considerable difficulties for rulers. Machiavelli discusses composite principalities, which are "not entirely new but a new appendage to an old state." In composite states disorders arise due to "one natural difficulty": when people revolt and welcome a new ruler in the hopes of improving their situation, they often belatedly realize "that they have made matters worse." This is because a wise prince "is always compelled to injure those who have made him the new ruler" in order to secure his control. Although a prince "needs the goodwill of the inhabitants" to enter a state, it becomes impossible to maintain the people's "friendship" following a conquest. Machiavelli illustrates this principle with the contemporary example of Louis XII's conquest and subsequent loss of Milan.
Discussing composite principalities, Machiavelli displays the brand of pragmatic ruthlessness that characterizes much of his book. Machiavelli again emphasizes the importance of gaining the people's goodwill, although he cautions that it will be impossible to maintain allies' "friendship" after a conquest. With this advice, Machiavelli highlights the fragile balance of power between a ruler and his subjects, urging princes to take the necessary steps to maintain the balance in their own favor.
Machiavelli adds, "When lands that have rebelled are reconquered they are not lost so easily," because a ruler takes advantage of the revolt by harshly punishing offenders and strengthening his state. Returning to the example of Milan, Machiavelli explains that the occupying French easily lost their conquest to the deposed duke, Ludovico, when he waged an initial war of reconquest. However, when France lost Milan after a second campaign, the "whole world" had to oppose her and various foes conspired against her. France lost Milan on both occasions.
Machiavelli pragmatically encourages rulers to use revolts in their favor, counseling them to take advantage of the opportunity to reassert their power and, if necessary, to reorganize their states. Machiavelli advises rulers to adopt harsh measures as necessary to secure their control over their subjects. The skillful use of arms and punishment forms an important component of governance.
Composite principalities are more easily maintained when the conquering and conquered states share the same country or language. Machiavelli writes that people typically "live quietly" as long as their "old ways of life are undisturbed." To maintain his new acquisitions in this instance, a ruler need only destroy the family of the old prince and refrain from altering the people's laws and taxes. In this way, the conquering state will easily absorb the new possessions.
Focusing on a unique kind of composite state, Machiavelli advises leniency when annexing similar territories. By refraining from altering laws and taxes, rulers will generally avoid negatively impacting subjects' lives and will thus earn their friendship (or at least avoid their hatred). On the other hand, deposed rulers must be dealt with much more swiftly and harshly.
However, when states with differing languages, customs, and institutions are acquired, the ruler's task becomes more difficult. In this case, both fortune and prowess must aid the ruler. In these instances, Machiavelli advises rulers to either live in the conquered state or establish settlements there. By living in the new state, a ruler "can detect trouble at the start and deal with it immediately." Settlements have the advantage of "little or no personal expense" and displace only a small minority of native inhabitants. Machiavelli advises rulers to avoid garrisoning large armies in new states, since the expenses are greater and the troops provoke hatred.
Machiavelli highlights the shared importance of fortune and prowess when securing certain types of composite principalities. In some instances, fortune and a ruler's prowess must work in concert to establish his position. Machiavelli urges princes to avoid stationing armies in new states, an action that alienates huge swathes of a conquered population. Rulers must sometimes opt for statecraft and settlements over shows of armed aggression.
Additionally, rulers in countries that differ from their own should endeavor to protect "smaller neighboring powers" and to weaken powerful ones. With this method, a ruler can protect himself against the threat of invasion. Machiavelli references the Romans, who grew their empire by conspiring with disgruntled natives in neighboring states. Machiavelli also cites the Romans' successful strategy in Greece, which entailed curbing the power of competing Greek states. Machiavelli praises the Romans for their "foresight," which allowed them to sense trouble well in advance and to remedy it before it became too widespread. Machiavelli compares political disorders to a "wasting disease," which at the start is "easy to cure but difficult to diagnose" and, if untreated, becomes "easy to diagnose but difficult to cure." The Romans never allowed problems "to go unchecked" to avoid a war, knowing that war "can only be postponed to the advantage" of opponents.
Using the metaphor of a "wasting disease," Machiavelli applauds those rare rulers who possess the prowess necessary to diagnose and cure the problems of their states. With these statements Machiavelli emphasizes the importance of prowess in a ruler. Machiavelli praises the ancient Romans' ability to secure and strengthen their holdings through the foresight of their rulers, who used a combination of armed force and cunning diplomacy to maintain the empire. Machiavelli advises princes to attack problems in a head-on manner—which often means launching physical attacks on opponents.
Machiavelli returns to his earlier discussion of Louis XII, analyzing the mistakes that he made during his Italian campaigns. Louis came into Italy at the behest of the Venetians, who wanted an ally in their campaign against Lombardy. When Louis conquered Lombardy, he suddenly found himself surrounded by many allies, having gained the friendship of the Genoese, the Florentines, and other small states. However, Louis made the fatal mistake of allying himself with the more powerful Pope Alexander, thereby alienating his smaller allies and weakening himself. Having made this first mistake, Louis was "forced to make others," eventually losing his foothold in Italy. Machiavelli demonstrates that Louis failed to follow the protocol for rulers of composite states. From this example he declares a general rule: "That whoever is responsible for another's becoming powerful ruins himself."
In both diplomacy and warfare, Machiavelli counsels rulers to focus first and foremost on the security and strength of their own position. Rulers must act only in a way that simultaneously fortifies their own power and weakens the influence of others. This task involves a combination of prowess and fortune, which Machiavelli implies that Louis XII lacked. According to Machiavelli, the weakness of the small Italian states and their necessary dependence on France would have made them much more useful allies to Louis than the already independent and power-hungry papal state.