John Pinofold explores the remarkable records in Oxford's libraries of the fight to end the transatlantic slave trade.

This year marks the 200th anniversary of the abolition of the slave trade, with the bill passing Parliament on 25 March 1807 and coming into force on 1 May. Hailed by W E H Lecky, the great nineteenth-century historian, as 'among the three or four perfectly virtuous pages comprised in the history of nations', the passing of the Act was the culmination of a long campaign by the Society for the Abolition of the Slave Trade, which had been fiercely resisted by those who had a vested interest in the trade.

Throughout the 1780s and '90s the abolition debate generated a flood of pamphlets as each side attempted to influence not just Parliament, but public opinion more generally. The Bodleian Library of Commonwealth and African Studies at Rhodes House possesses a substantial number of these pamphlets, together with several important manuscript sources, and is republishing a representative selection from each side of the argument to mark this year's bicentenary. Many of the documents will also be on display at Rhodes House in late April/early May.

The debate touched on many issues, including human rights, the economic well-being of Britain's West Indian colonies, the state of the British mercantile marine and the Royal Navy (seen as crucial at a time of war with France), the condition of the poor in England and, not least, the economic and moral condition of the African slaves themselves.

Central to the arguments of the abolitionists was the humanitarian issue. A Quaker pamphlet of 1784 stressed that 'justice and humanity' demanded an end to this 'inhuman business'. In their view, the greed and avarice of the traders was a fundamental cause of African slavery, and they also highlighted the inhumane conditions on board ship during the Middle Passage (the route taken by the trading ships from West Africa across the Atlantic), emphasising the frequent instances of floggings and rape, and the 'tight packing' of slaves below decks. A diagram of the slave ship Brookes was used to illustrate the latter and became one of the most effective images of the campaign.

The campaigners realised that it was not enough to appeal to people's emotions; it was also important to establish the facts. This led Thomas Clarkson, on his tour through England in 1788, to question some of those with direct experience of the trade, including slave captains and crewmen. The results appeared in his Substance of the Evidence of Sundry Persons on the Slave Trade, which is regarded as the first detailed account of the slave trade. In the book, the names of Clarkson's informants were left blank, perhaps to protect them from any form of harassment from their employers, but the Rhodes House Library copy has the majority of their names hand-written in, possibly by one of Clarkson's assistants who knew their identities.

The abolitionists realised that challenging the legitimacy of the slave trade could not be separated from questioning the legitimacy of slavery itself, for clearly the former existed only in order to feed the latter. Many of their publications, therefore, dwelt as much on the horrors of life on the West Indian plantations as on the conditions endured on the Middle Passage. They documented the brutality of the masters and overseers, the long working hours and inadequate periods of rest, and the poor diet and living conditions inflicted on the slaves. Here they drew very considerably on information provided by James Ramsay, whose manuscript journal documenting his involvement in the abolitionist movement is also held by the library. This contains the draft texts of several of his publications, some of his correspondence, and a series of model questions and answers, which were intended to substantiate through hard factual evidence what was essentially an emotional appeal. Ramsay's writings carried added weight because they came from someone who had first-hand knowledge of the conditions in the West Indies (as most of the abolitionists had not), as he had spent about 20 years there, as ship's surgeon and Anglican minister.

In 1784 Ramsay published An Essay on the Treatment and Conversion of African Slaves in the British Sugar Colonies, which exposed the appalling conditions under which the slaves in the West Indies lived and worked. This generated an enormous amount of interest, but also led to Ramsay being vilified by the planter community and their associates in England. Undeterred, he went on to write An Inquiry into the Effects of Putting a Stop to the African Slave Trade, in which he proposed that emancipated slaves should be settled on the African coast, where they could trade their produce for British manufactured goods. Thus a legitimate trade could replace an illegitimate one to the benefit of all parties.

The defenders of the slave trade, although motivated primarily by self-interest, were forced to address the humanitarian issue in their replies to the abolitionists. Their argument relied substantially on the assertion that the conditions under which the slaves lived in the West Indies were actually preferable to those under which they had lived in Africa. It was argued that most of the slaves were criminals or prisoners of war, whose fate at the hands of the African rulers was likely to be death or human sacrifice. Thus, transporting them to the West Indies saved their lives, and in return they owed a debt of service which was met by labouring on the plantations. Malthusian sentiments also played a part in this argument. It was stated that there was a surplus population in Africa, and that therefore the removal of much of this 'surplus' not only prevented the slaves from dying from starvation, but also allowed the living standards for those who remained in Africa to rise.

A second line of defence was that the living conditions of the slaves were better than those of the English working class. That this argument had an impact on public opinion is shown by a pamphlet in the collection written by 'A Plain Man'. The anonymous author believed that the slaves had 'each a little snug house and garden and plenty of pigs and poultry' and that it was 'a common thing to see at their feasts, fine fowls, very good beef, English bottled porter, and wine'. Misled in this way, it is easy to see why he should have wished that the English 'labouring poor were half as well off as the Negroes', and that 'we should in the first instance restore freedom to, and relieve the wants of our own poor'. There were many others who found such propaganda equally convincing.

Nevertheless, the cornerstone of the anti-abolitionists' case was economic. Starting from the premise that mortality rates in the West Indies were very high, they argued that, as 'Mercator' (in reality Sir John Gladstone, the father of the prime minister) expressed it, 'a constant supply of negroes from Africa is requisite to continue the cultivation of the islands'. It therefore followed that, without the slave trade, the lot of the existing slaves on the plantations would become worse, as they would 'no longer be joined by new recruits to share and lighten their burdens'. Moreover, if the labour supply dried up, the planters would emigrate and Britain would lose its West Indian colonies to France or the recently independent United States.

Although the abolitionists aimed to eradicate slavery itself as well as the slave trade, they accepted that the sugar trade was immensely valuable and that the West Indian islands should remain under British sovereignty. They argued that common economic interests would continue to bind the planters to Britain, and that British naval power should be sufficient to protect them from France or America. As to the labour question, Ramsay argued that had the slaves been treated with greater humanity, or even liberated, they 'would long ago have been so greatly multiplied as to have afforded sufficient numbers to have peopled the islands', and that it would be 'most profitable in the end if we begin even this late to treat them generally like human creatures'. Thus planters' economic arguments were neatly turned on their head.

The defenders of the slave trade also argued that if the British gave up this very lucrative trade, other nations would not be slow to take their place, and they might not treat their 'human cargo' so well. At a time of war with France, this fusion of supposed humanitarianism with nationalism was a compelling argument for many people. As 'An Individual of Little Note' wrote in a pamphlet: 'the French ... can only rise by our Fall, and our Ruin must be the Foundation on which alone they can establish their Greatness'.

More fundamentally, the anti-abolitionists defended the institution of slavery itself as part of the natural order, and, by selective quotation from the Bible, they also justified it as part of the divine order. This argument is presented in its starkest form in Scriptural Researches on the Licitness of the Slave Trade by the Revd Raymund Harris, in which he attempted to show that 'the Slave Trade is perfectly consonant to the principles of the law of nations, the Mosaic Dispensation and the Christian Law, as delineated to us in the Sacred Writings of the Word of God'.

The abolitionists were swift to respond to Harris's pamphlet, with Ramsay writing an Examination of the Rev. Mr. Harris's Scriptural Researches on the Licitness of the Slave Trade. In this, Ramsay ridiculed Harris's logic by showing that if everything in the Old Testament was accepted as the divine will, then crimes such as incest should be regarded as lawful, and he went on to argue that the New Testament amended and improved the human understanding of God's will. This point was reinforced by the Revd William Agutter of Magdalen College, who, in a sermon preached at Oxford in 1788, suggested that 'God winked at the times of that ignorance when men could not receive a purer law'.

Finally, the defenders of the slave trade claimed that it was an important nursery for British sailors, and that the Navy would suffer if it were abolished. The abolitionists had little difficulty in demolishing these claims. As Ramsay wrote: 'That the African trade is destructive to our seamen is known to every person who has an acquaintance with it.' Thomas Clarkson estimated crew mortality at about 20 per cent, and this has been broadly confirmed by modern research.

The abolition of the transatlantic slave trade was in many ways only the beginning rather than the end of the story. The abolitionists' ultimate aim was emancipation throughout the British Empire, but it was to take another quarter of a century of campaigning before this was achieved in 1833. Emancipation was not achieved in the United States until 1865 or in Brazil until 1888. Today, Anti-Slavery International remains the world's oldest human rights organisation, and is still actively campaigning against all forms of slavery worldwide. In 2003, after conducting the first national survey of slavery in Niger, the government of that country introduced a new law against slavery. Within the first six months of this measure coming into force, more than 200 were freed. The humanitarian concerns first raised by the abolitionists in the second half of the eighteenth century remain equally important in the first decade of the twenty-first.

John Pinfold Librarian, Bodleian Library of Commonwealth and African Studies at Rhodes House.