You might want to look up what the Romans actually did to Carthage before assigning that term to Reconstruction.
The aftermath of our WBTS was the mildest of any great civil war in history.
Unless you’d care to provide an example of one that was milder?
For example, exactly one Confederate was executed after the war for war crimes.
In Spain, which had a war in which the population, duration and number of dead is not dissimilar, 50,000 were executed in the first five years and at least another 150,000 died from mistreatment in prison.
Rome forced a harsh peace on Carthage in the 2nd Punic War before destroying it in the 3rd. The analogy here is that a harsh peace was imposed by the victor on the defeated, and that cannot be credibly denied even if the severity is debatable.
The Spanish Civil War had much wider participation- it was a flash point between fascism and communism (both nihilistic ideologies that sought annihilation of each other) particularly in regard to the involvement of Germany, Italy, and the Comintern. The American Civil War saw no such outside interference; the Falangists were also attempting to take control of the entire country whereas the Confederacy was attempting merely to leave the Union and form its own. The comparison, therefore, is quite tenuous.