Niccolo Machiavelli's Art of War was written in 1520 as a series of letters to Lorenzo di Filippo Strozzi. It is written in the form of a dialogue. Although Machiavelli is often most well-known for his work The Prince, The Art of War originally described the idea that war was a method of politics, a derivative view from that of Xenophon. This view was later popularized by Clausewitz. Machiavelli used the Art of War to advocate Roman strategies as a strategy for Italy to regain its power by increasing its military prowess and political strength, which Machiavelli saw as sorely lacking after getting the opinion that Italy's people were degenerate and corrupt.

There were seven books in Machiavelli's Art of War:

  • Book 1: In which fortune and virtue are described (translators have differed many times on whether these were the words actually meant by Machiavelli). It describes how to build the initial makings of a military structure, and highlights the Romans as a likely subject of study, as well as establishes the conversational style in which Machiavelli and his proponent, Fabrizzio (who may have been fictional), discuss military matters.
  • Book 2: In which initial armament and unit organization are described. These discussions supposedly provided the basis for Italian military unit planning. It again touches on virtue and fortune. Machiavelli takes a moment here to segueway into a discourse about how he thinks the Christian religion is responsible for making men more pacifistic and less warlike.
  • Book 3: Machiavelli discusses example battles and formations, and discusses artillery's value at length.
  • Book 4: A discussion in the style of Sun Tzu on the value of environment. Hannibal and Scipio are also touched on, in the sense of discussing their strategies of movement. The psychological condition of the troops are also discussed.
  • Book 5: This book is all about marching orders, communication, and ambushes.
  • Book 6: Encampments and intelligence are primarily discussed in this book. Special attention is provided towards health and medicine, as well as supply lines and force division of the enemy.
  • Book 7: Fortifications are discussed. Machiavelli strongly advocates the current French practices of fortification at that time in history. He writes a long discourse on the topic, as well as discussing the psychological use of fortifications.

Machiavelli's 27 Rules of Military Discipline are also presented in the appendix. After these are discussed briefly, he returns back to a discussion about reforms of Italian politics, naval discussions, and then some good old countryman hating. He again wishes that some Prince would follow his advice.