In The Prince, what, according to Machiavelli, are the disadvantages of the various routes to power?
Machiavelli discusses the prince's acquisition of power in relation to the acquisition of territories. He draws a distinction between hereditary and composite principalities. The acquisition of hereditary principalities presents specific advantages to the prince. The power structure has already been established, so the arrival of the prince is essentially the same as a change in watch. This provides the greatest advantage in that it requires very little political or military assertion on the part of the prince.
Composite principalities, however, demand much more from the prince. Authority is not clearly established in composite principalities. For this reason, the success of the prince's regime is not guaranteed. If matters in the principality do not improve under the prince, the future of the prince as well as those who helped him into power does not look very bright. This is perhaps the greatest disadvantage when a prince acquires a composite principality - authority has not been established.
With this, in composite principalities, the prince must go to greater lengths to establish his hold on it. He must not shy away from the use of cruelty as a means of establishing and retaining control. The prince also favors the use of a single ruler to that of a ruling class. In the case of the former, the prince must only eliminate the ruler's family, while a ruling class (Machiavelli uses the example of France) is much more difficult to bring under control.
The predominant theme of The Prince is the centralization of power in the hands of a single person, the prince. Disadvantages that arise from different circumstances, whether they be the nature of the prince's troops (mercenaries, reserves, et al.) or the nature of the principalities themselves (hereditary, composite, ecclesiastical, constitutional, et al.), stem from the degree of control the prince can exercise immediately. The more control the prince must establish, the greater the prince's disadvantages.