In the nineteenth century, leading public intellectuals like Alexis de Tocqueville of France, John Stuart Mill of Great Britain, and Senator Charles Sumner of the United States found the continued existence of slavery in the US unsettling. Tocqueville predicted a race war and lamented about the escalating violence in US politics over slavery. Although Tocqueville died prior to the beginning of the US Civil War, his written predictions engaged thinkers on both sides of the Atlantic had to answer as they watched the US Civil War unfold. This thesis uses Charles Sumner and John Stuart Mill of Great Britain to demonstrate the various reinterpretations of Tocqueville and American race relations in the 1860s and 70s. Though friends of Tocqueville, Mill and Sumner realized that an American race war had been a prediction too far. But both men did come to understand that the power imbalance between white and black Americans under slavery would prove long lasting in a manner that Tocqueville did predict. My research indicates that Mill and Sumner varied from each other as well. Before the coming of the Civil War, all three thinkers had argued that the US affirmed the possibility of a free society. By Reconstruction, only Sumner remained positive on this stance. Mill gave up hope, arguing that American politics depended so much on racial oppression that the nation would fail to give equal rights to African-Americans. Yet this difference embodied Tocqueville’s own ambivalence on the issue before the conflict had begun.