The modern slavery literature engages with history in an extremely limited fashion. Our paper demonstrates to the utility of historical research to modern slavery researchers by explaining the rise and fall of the ethics-driven market category of "free-grown sugar" in nineteenth-century Britain. In the first decades of the century, the market category of "free-grown sugar" enabled consumers who were opposed to slavery to pay a premium for a more ethical product. After circa 1840, this market category disappeared, even though considerable quantities of slave-grown sugar continued to arrive into the UK. We explain the disappearance of the market category. Our paper contributes to the ongoing debates about slavery in management by historicizing and thus problematizing the concept of "slavery". The paper challenges those modern slavery scholars who argue that lack of consumer knowledge about product provenance is the main barrier to the elimination of slavery from today's international supply chains. The historical research presented in this paper suggests that consumer indifference, rather than simply ignorance, may be the more fundamental problem. The paper challenges the optimistic historical metanarrative that pervades much of the research on ethical consumption. It highlights the fragility of ethics-driven market categories, offering lessons for researchers and practitioners seeking to tackle modern slavery.