A bold new look at war and diplomacy in Europe that traces the idea of a unified continent in attempts since the eighteenth century to engineer lasting peace. Political peace in Europe has historically been elusive and ephemeral. Stella Ghervas shows that since the eighteenth century, European thinkers and leaders in pursuit of lasting peace fostered the idea of European unification. Bridging intellectual and political history, Ghervas draws on the work of philosophers from Abbé de Saint-Pierre, who wrote an early eighteenth-century plan for perpetual peace, to Rousseau and Kant, as well as statesmen such as Tsar Alexander I, Woodrow Wilson, Winston Churchill, Robert Schuman, and Mikhail Gorbachev. She locates five major conflicts since 1700 that spurred such visionaries to promote systems of peace in Europe: the War of the Spanish Succession, the Napoleonic Wars, World War I, World War II, and the Cold War. Each moment generated a “spirit” of peace among monarchs, diplomats,