Yeah, I understand that that was the case with the USA, which is probably the slave country Engels was most acquainted with. But in other southern colonies freed slaves often still managed to get the right to property and sometimes became prominent and even racist themselves. Toussaint himself had been a prominent freedman in Saint Domingue before the revolution, and slave countries often had a separate “race” called “mulatto/mestizo” to designate people with both white and black ascendency. I mentioned the indentured servants there because they and future proletarians and craftspeople made such a big portion of the population as white people, compared to other slave colonies that had upwards of 60% of their population be black and/or slave. If I were to hazard a guess, that would be one of the reasons why the Settler States of Amerika managed to both pass and maintain so many explicitly racist laws, with a explicitly racist police force and constitution without immediately getting consumed in fiery revolution.