The impact of the American Civil War on Karl Marx, and Karl Marx on America. Karl Marx and Abraham Lincoln exchanged letters at the end of the Civil War. Although they were divided by far more than the Atlantic Ocean, they agreed on the cause of “free labor” and the urgent need to end slavery. In his introduction, Robin Blackburn argues that Lincoln’s response signaled the importance of the German American community and the role of the international communists in opposing European recognition of the Confederacy. The ideals of communism, voiced through the International Working Men’s Association, attracted many thousands of supporters throughout the US, and helped spread the demand for an eight-hour day. Blackburn shows how the IWA in America—born out of the Civil War—sought to radicalize Lincoln’s unfinished revolution and to advance the rights of labor, uniting black and white, men and women, native and foreign-born. The International contributed to a profound critique of the capitalist robber barons who enriched themselves during and after the war, and it inspired an extraordinary series of strikes and class struggles in the postwar decades. In addition to a range of key texts and letters by both Lincoln and Marx, this book includes articles from the radical New York-based journal Woodhull and Claflin’s Weekly, an extract from Thomas Fortune’s classic work on racism Black and White, Frederick Engels on the progress of US labor in the 1880s, and Lucy Parson’s speech at the founding of the Industrial Workers of the World.