but there were not very many cases of this happening after the ban. I read about the Clotilda decades ago and it was not a common event. The British also had naval patrols off the West African coast to prevent smuggling of slaves. Other than this, I largely agree with you that extanding slave importation would have resulted in a larger black population with more political power after the Civil War. Brazilians didn't ban slavery until the 1870s IIRC and there would have been demand for slave labour for the sugar plantations there. That's why I used Brasil as an example. The US situation of blacks (even those of mostly European ancestry) as a Dalit-like "polluted" caste doesn't exist in Brazil, and might be averted with a larger black population, meaning better lives for African-Americans.

The North and Midwest harboured resentment against blacks after the Civil War due to fears of job competition, and this persists even to this day in parts of Illinois, Ohio and Pennsylvania. Aside from a few hardcore abolitionists, the North did not fight the Civil War for the welfare of the blacks.

Yeah Lincoln was racist, but only to the same extent as any other typical Victorian. Blacks didn't "back" Lincoln if they were enslaved and unable to give him or the Union any support. And again, his assasination had no impact on US slavery, which was doomed once the Conferedates fired on Fort Sumter. By the time Lincoln was killed, the South had been beaten.