I wouldn’t be so sure about that. Larry’s textbook indicated Lincoln had little interest in Marx other than maybe a few correspondences, and aside from that, Marx and Engels’ letters indicated they actually thought the South had more potential for ginning up a French-style Revolution and clearly wanted that result.
Marx and Engels true to form, got their analysis wrong. They thought the federal govt couldn’t win because they couldn’t field the requisite 4 to 1 number of troops that had traditionally been required - only more like 3 to 1. What they failed to take account of were things like the railroads, industrialization and the federal govt having a standing navy while the CSA had to start building a navy from scratch.
Neither Marx nor Engels were all that influential at the time though they did both want the North to win. Lincoln was “the great centralizer” after all and they heartily approved of that.