A biographical study presents the life and labors of a French cardinal who emerged as a leading missionary organizer in North Africa, recounting his arrival in Algeria, appeals to colonists and clergy, establishment of missionary institutions and campaigns against slavery, and efforts to coordinate French religious presence alongside colonial expansion. The narrative situates his actions within political and ecclesiastical debates over colonization, outlines administrative initiatives, missionary ventures, and humanitarian projects, and assesses his influence on church policy and missionary strategy while tracing his personal convictions, public initiatives, and enduring institutional legacies.