Black slaves.....being slaves...were in no position to end slavery. The comment was beyond silly.
Slaves arrived in Jamestown in the 17th century; by the latter part of the 19th American slaves were, as you state, American, with no memory of Africa, and stayed where they were born.
Slaves were not "stolen" from Africa. They were sold, they were exported from Africa by African slave traders. The Slave Trade was a source of wealth for Africans who supported the International Slave Trade and opposed abolitionism. The only group in history that provided effective opposition to slavery was the WHITE race. The WHITE race ended slavery where it had the power to do so.
In Haiti, where slavery was especially violent and harsh, forty per cent (40%) of slaves were OWNED BY FREE BLACKS. Toussant L'OVerture, the father of Haiti, was a black who owned slaves. After achieving Haitian independence, Haiti's black leaders introduced forced labor. They didn't call it slavery though, but it was forced because most blacks wouldn't work unless forced to do so. See The Black Jacobins by ELR James, a black, WHITE hating communist from the Carribbean area who published this classic study of Haiti in 1938.
When the first 7 Southern states seceded in 1861 and held a convention in Alabama, they voted six to one AGAINST re opening the international slave trade. Only South Carolina voted for it. THERE WAS MORE POLITICAL OPPOSITION TO THE SLAVE TRADE IN THE CONFEDERACY THAN IN AFRICA, ASIA or THE MIDDLE EAST where slavery still is practiced today.
The black population exploded under slavery in the USA, even after the close of the international slave trade in 1808. The black population grew from 1 million in 1800 to 4.5 million in 1865 and it continued to grow until today. The only check on black population increase in the USA is the abortion rights movement, which has proven to be a blessing in disguise in that limited regard. In NYC, Black abortions exceed Black births. (!) "Black lives matter" is a catchy slogan, but black abortions matter more as a practical matter to the so called "Black Community."
As far as American blacks having no memory of Africa, the WHITE Europeans who developed Africa in the late 19th century has no "memory" of Africa either. They were explorers and pioneers who migrated to Africa while Africans clung to WHITE civilization as tightly as they could. Today we're lectured endlessly about the wonderful black "culture." If it's so wonderful, why do blacks run away from it to live next door to WHITE people today and why didn't they reclaim it in the 1800's when they could have done so?
Watch who you're calling silly. You're obviously not well read or well educated on this subject...and probably not on much of anything else for that matter.