Huju,
According to those that lived then you’re quite mistaken. In New York there was a Rabbi Raphall (who talked himself up to be bigger than he was) while supporting the Union said according to Judaism Slavery was OK. Baltimore had a Rabbi Illowy that supported the status quo on Slavery and backed the Confederacy. He was the biggest Talmud Chochem in America and we hold like some of his psaks today. The first Ruv in America was also in Baltimore. He didn’t say anything pro or against Slavery but I’d imagine if it was as immoral as you say he would of spoken up. 2 other middle of the road Rabbis spoke in general about peace even if it meant slavery continuing. There was one Rabbi in Baltimore that spoke out strongly against Slavery. That was the ultraliberal, ultraleftist Reform Rabbi. It seems from the Rabbis of that era your inline with the Reform Rabbi. You might want to reconsider
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