I'm reading Ira Berlin's 'The Long Emancipation', and in it, Berlin discusses historian Joao Perdro Marques' belief that slaves had little interest in universal emancipation, specifically because they had no knowledge of the notion. Marques then goes on to support his claim by stating that African-Americans went on to become slave owners as "maroons or free people of colour" after the civil war. How fair/valid is Marques' argument?
There are two assertions here: that slaves had no notion of universal emancipation and that free African-Americans went on to become slave owners after the civil war. The latter can be quite easily dismissed with the fact that the 13th ammendment was ratified in 1865 outlawing slavery in the U.S. (except as part of a prison sentence). In any case former slaves would be in no position to enter the slave market place as nearly all of them entered freedom with little money and property and no land.
The idea that slaves had no knowledge of universal emancipation is also not supported by evidence. The abolitionist movement in America had existed in some form since there was an America, and many early advocates were former or even current slaves. On of the most vocal groups; the American Anti-Slavery Society was founded almost 3 decades before the Civil War in 1833 and featured numerous African-American speakers in, as well as publishing narratives of slaves all while campaigning for emancipation. During the Civil war, slaves recognized the northern forces represented a chance at freedom, even before the emancipation proclamation became official policy. Thousands of slaves fled to union lines, often at great personal risk and that number increased after 1863 when the proclamation granted universal emancipation to all Confederate controlled territory (Union slave states would still have legal slavery until the passage of the 13th). The idea of slaves having little interest in emancipation is contradicted by there behavior over the century before the civil war, where many attempted to flee to free territory, buy their freedom, or bring lawsuits for their freedom when the opportunities were available. In fact one of the continuous complaints of slaveholders in the 19th century was that abolitionists like the AASS were riling up slaves and giving them ideas of emancipation (though of course, those ideas were always present within slave populations).
If you want to read more about the history of abolition in America I'd recommend checking out "A Slave's Cause" by Manisha Sinha