He is referencing the issue of slavery and the threat of it being outlawed in the United States. This fear was very real for southerners after President Abraham Lincoln was elected president in the election of 1860. Southerners feared that he would outlaw slavery across the United States.
This issue greatly affected the southern states, causing several of them to secede (leave) the US in order to form their own country. This would be called the Confederate State of America and this faction helps spark the Civil War.
They said that god created it but if that's not the answer then I believe that they also did not like Galileo for saying the sun didn't revolve around us.
In the Holocaust, they burned them in incinerators and mass pits. The survivors talk about the horrific black smoke that came out of the chimes and the smell of burning bodies. Horrible really.
