Abraham Lincoln, as president, chose to reply to an “Address” from the London-based International Workingmen’s Association. The “Address,” drafted by Karl Marx, congratulated Lincoln on his reelection for a second term. In some resonant and complex paragraphs, the “Address” heralded the world-historical significance of what had become a war against slavery. The “Address” declared that victory for the North would be a turning point for nineteenth-century politics, an affirmation of free labor, and a defeat for the most reactionary capitalists who depended on slavery and racial oppression.

Lincoln saw only a tiny selection of the avalanche of mail he was sent, employing several secretaries to deal with it. But the US Ambassador in London, Charles Francis Adams, decided to forward the “Address” to Washington. Encouraging every sign of support for the Union was central to Adams’s mission. The Emancipation Proclamation of January 1863 had made this task much easier, but there were still many sections of the British elite who sympathized with the Confederacy and some who favored awarding it diplomatic recognition if only public opinion could be brought to accept this.

The “Address” carried, beside that of Marx, the signatures of several prominent British trade unionists as well as French socialists and German social democrats. The Ambassador wrote to the IWA, explaining that the president had asked him to convey his response to their “Address.” He thanked them for their support and expressed his conviction that the defeat of the rebellion would indeed be a victory for the cause of humanity everywhere. He declared that his country would abstain from “unlawful intervention” but observed that “The United States regarded their cause in the present conflict with slavery-maintaining insurgents as the cause of human nature, and they derived new encouragement to persevere from the testimony of the working men of Europe.”