Antoine de Bourbon, Duke of Vendôme, King of Navarre and first prince of the blood, progenitor of the Bourbon dynasty, at the end of his life and in the following centuries acquired a negative reputation, especially among Protestants, for what they saw as the betrayal of their cause and of his own conscience in the pursuit of his fantom claims to the Kingdom of Navarre. This was accompanied by judgments formulated during his own lifetime of a frivolous and superficial man, lacking in judgment, though personally brave. He was also thought to have treated his virtuous wife Jeanne d’Albret, heroine of the Protestant cause, abominably. It will probably never be possible to reverse these judgments, although they should simply be noted as part of a historiographical tradition. In the process of compiling a new and as complete as possible edition of his correspondence (running to over 1250 letters), the present author concluded that a re-assessment of Antoine de Bourbon’s religious sensibility and dilemmas was both possible and useful in the context of the historiography of the Wars of Religion. De Bourbon’s correspondence adds nuance to his religious identity and places him firmly in the category of those who, while sympathizing with religious reform, saw themselves as pragmatic mediators, unconcerned with the doctrinal disputes of the time. This placed him in an impossible situation at a time when the religious controversy was only sharpening. Often regarded as an untested prince in the crisis of 1560-62, he was in fact an experienced provincial governor and military commander. His role as first prince of the blood, though undermined by Catherine de Medici’s capacity to manipulate the machinery of state, was of prime importance to a prince who regarded himself as a guardian of the royal succession and legitimate authority. He was also a prince firmly anchored in the dynastic world that precluded the abandonment of claims which historians have regarded as futile. This explains his obsession with the negotiations with the king of Spain over his wife’s inheritance and their inevitable effect on his decisions concerning religious toleration.