In the famed fifteenth chapter of The Prince, Machiavelli criticizes the writers of "imagined republics and principalities" for neglecting the effectual truth of politics. He claims that these writers are excessively concerned with how people should act and, as a result, fail to understand how people do act. Such a teaching, Machiavelli believes, ruins those who follow it because it leads to a concern with one's own goodness, rather than how to protect oneself from the many who are not good. Ultimately, Machiavelli's criticism can be boiled down to the simple idea that previous writers have ignored the study of "defense policy" or how to protect one's self or one's nation from hostile outsiders. The aim of this paper is to determine whether or not Machiavelli's criticism accurately applies to the teaching found in Plato's Republic, perhaps the most famous work about an "imagined republic." In order to accomplish this aim, I will examine the role that defense policy plays in the imagined city that Socrates and his young companions construct. Although the vast majority of the discussion in the Republic concerns the domestic policy of the city in speech, I will focus my analysis on two important passages in which Socrates and his interlocutors discuss defense policy. In the first (422a-423b), Socrates recommends a Machiavellian-style defense policy to deal with dangerous neighbors. In the second (469b-471c), Socrates modifies this policy to allow for friendships between naturally alike cities. In light of these passages, I will argue that the teaching of Plato's Republic does not ignore the study of how to protect oneself from hostile outsiders as Machiavelli claims. ..PAT.-Unpublished Manuscript [ABSTRACT FROM AUTHOR]