The slave trade was widely practiced among European countries into the1800s, slavery itself was far less prevalent. I read once that the cotton gin was in part responsible for the need for vast numbers of slaves in the South. Before the gin, many slaves were more akin to "house slaves" who did laundry and cooking etc.
My GUESS is slavery would have persisted in the South for some decades. The Planter Class controlled most everything and they needed it. I think over time some gradual measures might have come about to "soften" somewhat its appearance, like perhaps they would get paid a pittance, being treated somewhat more like mill workers in mill towns. In theory, one could eliminate the "property" aspect in the Code and still have slaves in any real aspect of the term. Mill and mine workers had it pretty hard too back in the day.
CWS no doubt has a better take, or can amplify on this topic.
Spaniards, Portuguese, Dutch, and British were all heavily involved in the slave trade. The French? Less so, if at all. The Spanish enslaved the natives, and when the natives died off, they brought in African slaves to do the work.
The first Africans brought to British America arrived at Jamestown in 1619 aboard a British privateer, which had seized them from a Portuguese slave ship. They appear to have been treated as indentured servants, although under harsher conditions of indenture than whites. The first formal enslavement was in 1640. Three indentured servants--2 white, 1 black--ran away and were recaptured. The whites got a year added to their terms of indenture; the black man was sentenced to a life of servitude.
Slavery was never legal in England after about 1200. Scotland had slavery--mostly mine-workers--until about 1800. The British abolished the overseas slave trade in 1807, as did the USA, leading the rest of the world.
For nearly 1,000 years, southern and eastern Europe suffered periodic slave-capturing raids from Muslim polities in North Africa, the Middle East, and southwestern Asia.
Slavery in the American South was a millstone economically by the time of the Civil War. It existed as an all-encompassing social institution because it met the needs of white people in that respect.
It's hard to guess when slavery in America would have ended had the Confederacy gained its independence. The CS Constitution enshrined slavery (although it prohibited the overseas slave trade) and states were not free to prohibit it within their borders. That makes me think that it would have gone on into the 20th century. And that the South would have had an even more stagnant, retrograde economy than it did in fact for 100 years after the Civil War.
It's interesting how historians' opinions on how long the South would have kept slavery tend to track with their views about Lincoln. Pro-Lincoln historians tend to see the institution of slavery lasting longer than anti-Lincoln historians do. The early 20th century, the Progressive Era, was a time of scientific racism. Historians of that time tended to portray Lincoln in particular and the North in general as being wrong-headed in prosecuting the Civil War and liberating black people. Woodrow Wilson, born and raised in Virginia, whose father had been a Confederate chaplain, was a great example of that mind-set. America's "first great motion picture,"
Birth of a Nation, of 1915, reflects that point of view. The 2nd iteration of the KKK--the "we hate Jews and Catholics too" version--began in 1915 as well, with the famous ceremony on Stone Mountain.
Eugenics was a very popular field of "scientific" study during that period too. And not just in the USA. Wilson, T. Roosevelt, Margaret Sanger, and Churchill, to name a few prominent people, were true believers.
