Apologies if this is a rather strange question but it's been on my mind lately. Living in the South, I've met a wide variety of people but I recently met some "Lost Cause" neo-Confederate sympathizers and what they had to say about President Lincoln was very strange. Aside from their obvious hatred of Lincoln for his domestic policies, they claimed that he was a friend of Karl Marx and that they wrote letters to each other.

I never really thought about it but Marx would've been around the height of his career around the time of the civil war. Is there any truth to Marx and Lincoln writing to each other? If so, or even if not, is there any evidence that Lincoln knew of Karl Marx and had an opinion of him?