Christopher Leslie Brown's task in this ambitious project is to reexamine the emergence of the British abolitionist movement in the late eighteenth century. The emergence has been oft described but, in Brown's view, inadequately explained. Too often, he avers, the decision to mobilize actively against slavery and the slave trade has been seen as a predictable outcome of shifts in moral perception. Yet most historians of the subject have devoted relatively little attention—and in at least one celebrated case, that of Eric Williams (whose Capitalism and Slavery remains one of the pillars of abolitionist historiography), none at all—to the movement's antecedents. Rather than seeing abolitionism as “an obvious and logical thing to do,” therefore, Brown proceeds on the assumption that antislavery organizing, in this time and place at least, “was odd rather than inevitable … a contingent event that just as easily might never have occurred” (30).

Brown's agenda thus differs markedly from that of previous generations of abolitionist scholars. His purpose is neither to validate nor to discredit the traditional humanitarian account of abolitionist achievement but rather to fashion an explanation that profiles the movement's diverse and conditional origins. Those who strove to end slavery were not born abolitionists, he insists, but became such over the course of their lives. It is the process of becoming that primarily interests him.

At the core of his explanation lies the American Revolution. Prior to assessing that event's significance Brown traces the development of antislavery sentiment in the pre-Revolutionary era when the slave system was enjoying spectacular success in the North Atlantic world. Brown investigates in detail a number of distinct episodes—including the debate over whether to admit slavery into Georgia and the decision by Quakers to expel slaveholders from religious fellowship—when the morality of colonial slavery was challenged, culminating in the celebrated Somerset case of 1772. Despite the ambiguities of Lord Mansfield's verdict, the case was nonetheless significant in that it “promoted an intensive public discussion of the rights of slaves and slaveholders and called attention to the peculiar character of the colonial labor system” (98). But Brown's point here is that Somerset was ambiguous in more ways than one. Whatever its status on English soil, the legality of colonial slavery appears to have been taken for granted by most participants in the case. Indeed all these episodes demonstrated what he calls a “defensive spirit” (79) in which the banning of slavery from certain areas or communities went hand in hand with an acceptance or even insistence that it would continue elsewhere.

The power of colonial slaveholders remained largely intact on the eve of the American Revolution, therefore, notwithstanding the moral opposition that had been voiced so persuasively by their enemies. But the Revolution marked a turning point in both British and American responses to slavery, and it did this, in Brown's view, primarily by affording the opportunity for abolitionism's political deployment. All parties to the imperial contest discovered in slavery an instrument for the validation of their own worth and the simultaneous discrediting of their opponents’. As Brown puts it: “The American conflict offered up identifiable villains: colonials who cried out for liberty but denied freedom to their slaves, British statesmen who honoured the interests of African traders and prevented colonials from curtailing slave imports. … By describing complicity in slavery as proof of collective vice, disputants in the Revolutionary era helped define opposition to slavery as proof of collective virtue” (153). Pragmatism and principle also combined to integrate arguments about slavery's future into a wider reconsideration of British imperial behavior and obligation and here Brown provides an important reassessment of Granville Sharp. By suggesting that Sharp was “not selective enough” (199) in his moral targets during the 1780s, Brown notes that his remonstrations against colonial slavery and the slave trade invariably took second place to protests against the American war and especially the fight for parliamentary reform.

The second half of Brown's study concentrates upon the search for solutions. To validate arguments against colonial slavery, reformers needed to provide practical alternatives to a system that had proved hugely beneficial to its administrators. Early emancipation proposals were largely shaped by a belief in the efficacy of imperial rule, which in part explains their failure, and in the 1780s the emphasis of reform shifted away from colonial slavery toward the slave trade. In an outstanding discussion, Brown next demonstrates how the various strands of imperial reevaluation, moral reassertion, and economic realism came together in colonization schemes along the West African coast. Now, for the first time, he also moves to a consideration of black agency. Brown rightly cautions against expecting too much from blacks in late eighteenth-century Britain who, Olaudah Equiana notwithstanding, had neither the knowledge nor the independence to enlist actively in abolitionist ranks, and his conclusion that, most often, blacks “aspired less to abolish slavery than to escape from its clutches” seems apt (298).

In his final two chapters Brown charts the development of British evangelical and Society of Friends’ mobilization against colonial slavery and the slave trade in the 1780s, highlighting again how morality and practicality fused in complex and contingent union. True to his mission of investigating the process of becoming, he notes how previous accounts have failed to notice and thus explain the “vast gulf between the reluctance of English Quakers to act in the 1770s and their enthusiasm for abolitionism in the years after the American war” (405). As in the rest of this fascinating study, Brown reveals an exceptional ability not only to ask the right questions but equally to provide answers that are in themselves both persuasive and stimulating of further inquiry. Moral Capital is an exceptional achievement, a major contribution to the historiography of antislavery mobilization in late eighteenth-century Britain and the North Atlantic.