In 1677, the Jesuit prelate in Rio de Janeiro, Father Silveira Dias, summarily excommunicated every distinguished member of the city’s municipal council. Although priests frequently quarreled with local officials over such issues as control of indigenous labor, marching order in annual processions, or the extent of clerical exemption from municipal taxation, only in the most extreme scuffles did clerics make heretics of the local elite. In this case, the Jesuits exercised excommunication, their ultimate weapon, in defense of a fetid mangrove swamp.1
This was not an isolated instance. In the next decade, the Benedictines and individual landholders, with respective threats of excommunication and arrest against trespassers, pursued exclusive claims to the mangrove forests that bordered their lands on Rio’s extensive Guanabara Bay.2 As a result, the bay’s wretched free poor—abruptly barred from a resource that had supplied much of their food and had been traditionally open to all—appealed...