Generally speaking manufacturing companies in the North were large customers for Southern cotton for their textile mills. Slavery provided the workforce in the cotton plantations and Northern business men had no problem with the South's slavery. The cotton was easily sent to the North and the fact that slaves were not paid, more than likely reduced the costs of cotton for the North. In addition, freed Blacks in the North had no political rights. Keeping slavery intact was one way of avoiding the problem of dealing with former slaves, whom many in the North deemed to be the lower strata of society.
The North believed in a free labor system and the South believed in a slave labor system.
Slaves were only in the south. None in the north.
south
south
It was unpopular in the north because they did not support slavery, and therefore did not want to send escaped slaves back to the south
He was a slave for the south.
the south owned slaves
South
North dislike The Fugitive Slave Law, because that did not support slavery, and therefore did not want to send escaped slaves back to the south. North brought the slavery issue to their own doorstep , and gave the runawys a heroic victim status.
The reaction in the North against the Fugitive Slave Law and Uncle Tom's Cabin upset people in the South because it highlighted the divide between the two regions on the issue of slavery. In the North, there was strong opposition to the law and support for abolitionist literature like Uncle Tom's Cabin, which portrayed the harsh realities of slavery. This angered the South, as it felt its way of life and economic system were being threatened by Northern agitation against slavery.
Frederick Douglass did not actually fight for either side. He advocated for the abolition of slavery. He was, however, an adviser to Abraham Lincoln.
The slaves headed to the union so which was in the north.