Both living in London for more than twenty years (1849- 1873), Karl Marx and J.S. Mill commented extensively on the features and contradictions of American society and politics. In particular, the two thinkers devoted a substantial number of letters, articles and systematic writings to the issue of slavery and to the events of the Civil War at the beginning of the 1860s. The literature has never compared their philosophical-political questionings of post-Tocquevillian America, nor has it investigated the continuities in and ruptures between their analyses of the slavery-based American economy and society. Consequently, the author focuses specifically on their American writings in an attempt to cast light on some significant similarities between the two philosophers when addressing their European readers on the American Civil War and the central issue of slavery. Although embedded within different moral and political languages, their understandings of slavery pursued a twin goal: to reveal how relevant the categories of "race" and "class" vis-à-vis State sovereignty and the development of modern democracy had become since Tocqueville, and to point out the very close linkage between the American events and the fate of Europe as far as labour movements were concerned. From such a perspective, in the author’s view, they urged their European readers to go beyond the military façade of the Civil War and develop a broader theoretical perspective on what was really at stake on the other side of the Atlantic.
Keywords: Mill (John Stuart), Marx (Karl), slavery, American Civil War, civilization, despotism, revolution