Law reconstructs Roman Catholic missionary work in the West African kingdoms of Allada and Whydah from the 1650s to the Dahomian conquest of the 1720s, using Spanish and French missionary correspondence, the documentary compendium assembled by Antonio Brasio, and later European traders' accounts. Missions repeatedly began well and repeatedly collapsed, and he asks why. Most of the invitations came from local rulers, who wanted priests for literacy, for advantage among competing trading nations, and above all for ritual power believed to work against thunder, war and demons. Conversion stalled on the demand that a king renounce polygamy and the older cults, on the need for consent from chiefs whose standing rested on those cults, and on hostility from English and Dutch traders who feared a French Catholic ascendancy. Reading the 1658 Doctrina Christiana of Allada, Law argues that local people came to identify the Christian God with the creator Mawu, so conversion meant reordering an existing pantheon.