David G. Haglund's Sister Republics tells the story of the unique relationship between the United States and its first ally, France. Historians and political scientists have characterized interactions between the two countries in the spheres of security and defense policy in radically different ways: either the two comport themselves in a highly cooperative fashion, befitting their status as old allies and steadfast friends, or they act as bitter rivals, revealing their alliance to be at best dysfunctional and at worst destructive. Haglund uses a fresh approach to reconcile these divergent positions, examining the Franco-American bond through the prism of strategic culture. In doing so, he reveals the cultural factors that have contributed to the suboptimal relationship between the two nations.