Why Was Slavery Abolished? A Historical Materialist Analysis

The dominant liberal account of slavery’s abolition presents it as a triumph of moral progress — a slow but inevitable awakening of conscience culminating in legislative action. In this narrative, British abolitionists, motivated by Christian values and Enlightenment ideals, waged a principled battle against an evil institution, eventually winning out through moral persuasion and political reform. Yet this account ignores the material conditions and structural dynamics that underpinned slavery’s demise. From a historical materialist perspective, the abolition of slavery must be understood not as the result of moral enlightenment, but as the outcome of economic transformation, geopolitical strategy, and the evolving requirements of capitalist accumulation.

Slavery was never simply a moral failure — it was a specific form of labour exploitation rooted in an earlier phase of capitalist expansion. In the 17th and 18th centuries, the plantation economies of the Americas, particularly in the Caribbean and Brazil, generated immense profits for European powers. Enslaved African labour was indispensable to sugar, tobacco, and cotton production. Britain, France, Portugal, and Spain all enriched themselves through systems of chattel slavery, which commodified human beings as property and generated surplus through direct coercion.

The abolitionist movement in Britain culminated in the 1807 ban on the transatlantic slave trade and the 1833 Slavery Abolition Act. These developments coincided with Britain's consolidation of naval supremacy and the expansion of its industrial capitalist base. While public campaigns were morally driven, their success can’t be disentangled from Britain's interest in undermining rival colonial powers such as Brazil, Portugal, and Spain, who were still heavily reliant on slavery.

Brazil remained the world’s largest slave importer well into the 19th century and a major sugar producer. Britain’s anti-slavery treaties, such as the 1845 Aberdeen Act, empowered the Royal Navy to intercept slave ships — targeting Brazilian and Portuguese economic interests under the guise of moral high ground. A notable example was the seizure of the Brazilian slave ship Felicidade in 1849 by the HMS Cressy, a case that caused significant diplomatic tension and disrupted Brazilian slave logistics.

The Spanish Caribbean, particularly Cuba, was a leading sugar exporter. Spain began abolition gradually only after the decline of the Cuban sugar boom and under British diplomatic pressure. Cuba would not formally abolish slavery until 1886, long after Britain's global enforcement had curtailed transatlantic trade.

By the late 18th and early 19th centuries, slavery as a labour system was increasingly seen by sections of the British bourgeoisie as inefficient and incompatible with the requirements of industrial capitalism. Unlike wage labour, slavery tethered workers to a single location, prevented the flexible allocation of labour across sectors, and discouraged innovation due to the fixed costs of maintaining enslaved people. Industrial capitalism, by contrast, required a mobile, “free” workforce — one that could be hired and fired, disciplined by the threat of unemployment, and made to sell their labour-power in order to survive. The abolition of slavery was therefore not a negation of exploitation, but a transition to a different, more dynamic and productive form of it.

The compensation paid to slaveowners in 1833 — about £20 million (equivalent to billions today) — was one of the largest public bailouts in British history. It allowed major slaveholding families and financial firms to reinvest in industrial ventures. Barclays and Lloyds, both linked to slave-era finance, later became major banking institutions. A portion of the funds also went into infrastructure such as railways and mining operations, further advancing industrial capitalism.

Major British banks and insurance companies, many of which had underwritten slave shipments, now reinvested in industrial ventures. Their support for abolition stemmed from the declining profitability of slavery and a desire to legitimise British finance.

As Marx observed, capital does not abandon forms of exploitation out of compassion. It transitions when a more efficient form becomes available. As industrialisation advanced, the rigidities of slave labour became a barrier to the generalisation of wage labour and commodity production. Abolition, then, was a necessary adaptation to the needs of an evolving capitalist economy.

Britain’s turn to abolition also served its strategic interests in the global arena. By the early 19th century, Britain had already begun transitioning away from slavery, having benefitted immensely from the wealth it had generated. Other imperial powers, especially Portugal and Spain, continued to rely heavily on slave labour. Brazil was the largest importer of enslaved people, and Cuba was the most productive sugar exporter, both using slave labour well into the mid- to late-19th century. In this context, British abolitionism functioned as an economic weapon and a tool of moral imperialism.

By promoting abolition internationally and using its navy to suppress the transatlantic slave trade, Britain undermined the economic competitiveness of its rivals. Naval patrols were deployed under the guise of humanitarian intervention but acted effectively as instruments of economic warfare. Meanwhile, Britain pushed new markets and trading partners toward wage labour systems, aligning with the industrial economy it now dominated.

This geopolitical dimension explains the otherwise curious timing of British abolition. If the motive had been purely moral, one would expect slavery to have been abolished while Britain remained deeply dependent on it. Instead, the shift occurred when slavery had become more useful to its rivals than to Britain itself. In this way, the abolitionist movement was not merely a humanitarian campaign — it was also a convenient ideological cloak for imperial assertion.

The structural transformation of labour relations also played a critical role in rendering slavery obsolete. As capitalism matured, it demanded not just more labour, but more disciplined labour — labour that could be reorganised, re-trained, and relocated according to the needs of production. Wage labour provided that flexibility. The formal “freedom” of the worker masked a deeper compulsion: under capitalism, workers are “free” only in the sense that they are no longer the legal property of their masters, but are instead compelled by economic necessity to sell their labour-power to survive.

The abolition of slavery made possible the formal equality of persons under the law — an equality which capitalism requires in order to function ideologically. The worker and the employer enter into a “contract” as equal parties, obscuring the power imbalance between capital and labour. This ideological function was essential to the consolidation of bourgeois hegemony.

In this sense, abolition was a necessary ideological transformation that legitimised a new, more productive form of domination. It was not the end of exploitation but the refinement of it.

If slavery’s abolition was materially driven, how do we explain the powerful moral discourse that accompanied it? Here, Gramsci’s concept of hegemony becomes crucial. Hegemony refers to the cultural and ideological leadership exercised by the dominant class — the ways in which ruling interests become internalised as common sense. In this context, moral arguments against slavery helped to win popular consent for changes that ultimately benefited capital.

The elevation of abolition as a moral cause allowed the British state to unify sections of the middle and working classes around imperial objectives. The image of Britain as a “liberator of the enslaved” helped deflect attention from the ongoing exploitation of labour at home and the violent domination of colonised peoples abroad. It also helped consolidate national identity in a period of domestic upheaval.

In short, the moral discourse of abolition played a dual role: it facilitated a shift in labour relations and legitimated British imperialism. It did not challenge capitalism but rather helped it adapt and expand.

Understanding the abolition of slavery through a historical materialist lens allows us to see through the mystifications of liberal history. It reveals that systemic change is rarely, if ever, the result of moral awakening alone. Rather, it is driven by contradictions within the economic base, shifts in productive forces, and strategic recalibrations of ruling class power.

Today, moral discourses are still mobilised to legitimise the actions of states and institutions — whether in humanitarian interventions, trade policies, or domestic labour reforms. As trade unionists, socialists, and educators, we must ask: whose interests are being served, and what material conditions make these shifts necessary?

The challenge is not simply to win moral arguments, but to build class power capable of transforming the system itself. As long as capitalism persists, it will continue to generate new forms of exploitation, each cloaked in the language of progress and freedom.