One way to look at it is to ask, “How many countries used a Civil War to end slavery?”
I’m guessing the answer is...one!
That would suggest alternatives were possible.
Im guessing the answer is...one!
Haiti: Violent revolution to get rid of slavery.
Brazil: Emperor overthrown because of slavery.
Most new world lands with slavery were either colonies that had to go along with what the mother country decided, or they had so few slaves that slavery wasn't much of an issue.
But in fact, in many countries, emancipation happened during or after the bloody wars for independence from Spain.
However you look at it the answer was more than one.
Still another way to look at it is to ask, "How many countries had region willing to launch a bloody rebellion to protect their institution of slavery?" The answer to that is one also.