From the sixteenth century, the ideas of the Reformation spread across the Loire estuary and particularly to the town of Nantes, which represented the main French port until the middle of the eighteenth century. Maritime traffic and the Dutch presence contributed to the establishment of Protestants there, notably through their association with the salt trade. The Loire estuary represented a strategic component of the Protestant prince Henry of Navarre’s opposition to the powerful ultra-Catholic League long before the signing of the Edict of Nantes in 1598. When the Edict was revoked, the Protestants dispersed but resettled in Nantes and surroundings beginning in the middle of the eighteenth century. The Loire was still essentially the reason for their return, and it is through its estuary that a “Port Protestantism” links the sixteenth to the twentieth centuries.