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Lincoln and Marx became mutual admirers in the early 1860s due to the latter’s work as a foreign correspondent for The New York Daily Tribune. From 1852 until the start of the Civil War, Marx, sometimes with Engels, wrote “over five hundred articles for the Tribune,”
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Early in the war, he championed the Union cause, even before Lincoln decided on emancipation as a course of action
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https://www.openculture.com/2022/01/how-karl-marx-influenced-abraham-lincoln-and-his-position-on-slavery-labor.html