"The Ashburton Capitulation": The Convention of London, British Defeat, and the Americanization of the Atlantic, c. 1842

Two dimensions of Atlantic slaving paths in need of rethinking are those of time and jurisdiction. Despite longstanding scholarly currents, the Atlantic world neither ended in the 1820s nor excluded the antebellum American republic. Indeed, by so limiting its vision of the Atlantic, existing scholarship misses the remarkable story and implications of the failed Convention of London of 1841. Also known as the Quintuple Treaty, the convention meant to transcend obstacles of international law that hindered British efforts to suppress the transatlantic slave trade. As understood by the convention’s author—Lord Palmerston, Foreign Minister of the Whig Melbourne ministry—what Britain most needed to suppress the trade (aside from abolishing demand for slaves in the Americas) was to shift the burden of proof from searcher to searched by deleting the right of search from the law of nations. By co-signing the convention with the governments of France, Prussia, Russia, and Austria—together thought sufficiently hegemonic in the early industrial Europe to codify such changes—Britain and Palmerston intended to do just that. In fact, the convention and British hopes for effective multilateralism would have succeeded if not for American diplomacy. According to Henry Wheaton—famed American jurist and author of the distinguished text of his day Elements of International Law—the defeat of the Convention of London constituted a pivotal moment: “The policy of the United States may consequently be said...perhaps for the first time to have had a most decisive influence on that of Europe.” But the most decisive influence was felt much farther south, as American defeat of the Convention of London resulted in the prolongation of Atlantic slaving paths for more than a quarter century. In so doing, the United States “Americanized” the Atlantic by defeating humanitarian multilateralism in the name of—and by projecting—unilateral freedom.