The Franco-Swedish Phase and the Peace of Westphalia

Under Cardinal Richelieu, France openly entered the war against Spain and the Empire in 1635, an intervention that transformed the conflict into a struggle that was primarily political rather than religious, since Catholic France allied itself with Protestant Sweden against the Catholic Habsburgs. The Battle of Rocroi in 1643 marked the definitive end of the Spanish tercio infantry's century-and-a-half of military supremacy. Widespread exhaustion among all the powers drove peace negotiations that began in 1644, held simultaneously in the Westphalian towns of Münster, where the Catholic powers negotiated, and Osnabrück, where the Protestant powers did, and involving representatives of more than one hundred political entities. The treaties were finally signed on 24 October 1648.