Thucydides on International Law and Political Theory demonstrates that in classical times, especially in the era of the Peloponnesian War, international law and strategy existed in an advanced form among the city-states of ancient Greece. It shows how the work of Thucydides and classical Greek international law and politics have influenced aspects of modern international law and international politics. Iacovos Kareklas extensively analyzes Thucydidean political realism and indicates how it differs from modern realist and neo-realist theories of politics and presents that the “just war” theory of Thucydides’s time formed the legal and political basis of contemporary kinds of military intervention. Further, interstate treaties as listed in the work of Thucydides are categorized, interpreted, and commented upon. The military strategy of classical Greece and the role of religion in foreign policy decision making are also emphasized.