The famous historian Carlo Sigonio taught at the University of Bologna between 1563 and 1584. During this period he published several works on the medieval history of the city and of Italy which included a stronger political interpretation than found in his previous works on Roman and Greek antiquity. His history of the Italian cities and states focused on the concept of republican libertas, and underlined the conflict between them and the temporal power of the Pope.While Bologna was subject to that temporal power, the city was rife with republican tensions, with the Bolognese magistracies' coming into open conflict with the institution of the Church in Rome.This paper will examine Sigonio's political thought in the context of the broader struggle between the Senate of Bologna and the State of the Church, and will explore the role played by the historian in supporting the republican side of the debate.