The classical doctrine of civil war had a second coming in the scholarly writings of international lawyers. This began in the 1890s around the time of the Chilean and Brazilian naval revolts and the Spanish-American War of 1898. Members of the new cosmopolitan profession of international lawyers sought to formulate a branch of international law to manage the phenomenon of civil war, combining the elements of belligerent recognition, recognition of insurgency, the laws of war, intervention, and state responsibility. Doing so, they produced something of a francophone synthesis of the classical doctrine of civil war at the turn of the century. This chapter explores the gradual process of this synthesis, from the writings of Carlos Wiesse and Antoine Rougier to the work of the Institut de droit international. However, it then concludes with an overview of the great disillusionment of the 1930s and shows how the legal debates during the Spanish Civil War laid bare the bankruptcy of the classical doctrine.