This article explores the Royal Navy’s unique use of enslaved labour in its naval yards in Jamaica during the eighteenth and early nineteenth centuries, highlighting how the Crown’s pursuit of naval supremacy was built in part on the forced labour and skills of the African diaspora. Beginning in 1729, under the direction of Rear Admiral Charles Stewart, the Royal Navy shifted from hiring enslaved workers from local populations to purchasing them outright for Crown use, establishing a workforce that included both men and women. Stewart’s pronatalist policy aimed to secure a self-replenishing labour supply by encouraging the birth of children who would also be enslaved in service to the navy. Over more than a century, these “King’s Negros” were trained in European shipbuilding and maintenance, transferring valuable technical knowledge while enduring harsh conditions and a life of bondage. The article provides a microhistorical lens on the Atlantic world, focusing on the lived experiences of these enslaved individuals and their unintended role in bolstering Britain’s naval power. By examining the origins, conditions, and legacies of this workforce, the article contributes to broader discussions on slavery, imperialism, and the global reach of military-industrial enterprises in the Atlantic era.