Thanks for sharing your thoughts. You bring up some interesting points, one being the effect the EP had on England. William Wilberforce and his tireless work really made it a sticky subject for English society, supporting the south. And I have read, that if not for a speech by John C Calhoun giving a sympathetic rationale for slavery in the 1830’s, we might very will have freed the slaves here before the war.
Fascinating to study this period of history.
1859 - Charles Darwin published his racist masterpiece On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (yes there's a reason we're not told the full title). It basically pushed scientific racism, particularly given that an attack on God's existence during the Christian abolitionist movement in English speaking countries as tantamount to an attack on abolition itself. Just to make sure people understood that natural selection applied to people as much as animals (in Darwin's view), Darwin wrote his observance of red ants using black ants as slaves and his belief that if not for slaves the red ant colony would cease to exist. The so-called "enlightenment" movement's new hero was making the case for putting blacks back in chains in England and keeping them in chains elsewhere. (Years after the civil war Darwin wrote his sequel The Descent of Man in which was all about connecting the dots between natural selection and treating non-whites as 2nd class people.)
1860 - In the U.S. the Christian abolitionist party, known as the Republican Party, won not just the WH but also retained control of the House (Dims won the Senate, though that changed after the the CSA states seceded leaving a Republican majority).
1861 - The Dim controlled southern states seceded and confederate Dim leaders in South Carolina began attacks on Fort Sumter's supply ships in January (while Dim president Buchanan was still in the WH because Lincoln wasn't inaugurated until March). One could argue the civil war begin as Dim president Jefferson Davis of the CSA vs Dim president Buchanan of the USA. Before Lincoln took office, Davis ordered the full attack on Fort Sumter (though the attack didn't take place until Lincoln was in office).
You bring up the 1830's. A pastor named Theodore Weld was an awesome abolitionist. If you want to give one name to the 19th century abolitionist movement who had no political power, it'd be him. He was basically Calhoun's antagonist. Weld wrote The Bible Against Slavery and made the case that slavery in the Old Testament, as grotesque as the OT seems to us NT believers, was nicer to slaves than the chattel slavery of the U.S. because at least in the OT slaves had rights. The abolitionist movement faced horrible censorship in the south, most notably with Dim postmasters. Weld realized that not even Dims would dare to block Christian ministers from communicating with each other. Thus, Weld's books and speeches would be directed mainly toward Christian leaders in the north, knowing that those leaders had communication with Christian leaders in the south. He also earned the nickname "the most mugged man in America" by giving speeches in the "south" (which meant Ohio and Pennsylvania, because he'd probably be killed for giving abolitionist speeches further south). He founded the Abolitionist Society and they built a building in Philadelphia across from Independence Hall (not "across" towards the Liberty Bell, across 90 degrees to the right I believe). Ever been to the abolitionist society bldg when touring Philadelphia? Neither have I because it was torn down by Dim sympathizers after Weld and his wife married in the building. To this day a lot of Catholic historians credit the abolitionist movement mainly to Protestant leaders, while most atheist historians hope we forget the "enlightenment" crowd's scientific racism.
One final piece of trivia nobody thinks about. Imagine being born in Texas around year 1800 and living there your entire life, if you were blessed to live at least 70 years. Your citizenship would change many times over. Born a citizen of Spain (Texas was "northern frontier" territory of the Spanish empire), then became a citizen of the new nation of Mexico in the 1810's when Mexico seceded, then a citizen of the Republic of Texas in the 1830's when Texas seceded from Mexico, then a U.S. citizen in the 1940's when Texas joined the U.S., then a citizen of the Confederate States of American when Texas joined the CSA, then back to being a U.S. citizen at the end of the civil war. LOL