Abraham Lincoln and Karl Marx were contemporaries who influenced one another. This is a more accurate article than the similarly-themed article in the Washington Post. I found it interesting that Marx was a regular contributor to The New York Daily Tribune which was the most influential Republican newspaper of the time.
Lincoln and Marx by Robin Blackburn (Jacobin Magazine)
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.
Here’s a link to the actual letter and the response sent by Ambassador Adams:
https://www.marxists.org/archive/marx/iwma/documents/1864/lincoln-letter.htm