re: BLM and the Chicago Kidnapping/Torture Case

"I have no purpose, to directly or indirectly, to interfere with the institution of slavery in the States where it exist."
Abraham Lincoln first inauguration
The Emancipation Proclamation was about keeping Europe (mainly England) from entering the war on the side of the Confederacy cause England had been having communications with the CSA.
The common Northerner or Southerner wasn't worried about a slave or slavery when they was trying to kill each other on the battlefield.
The rich slave owners and government officials didn't want slavery to end cause cotton was a big economic resource, northeners and free blacks did also own slaves.
A southerner like Robert E Lee in Northern Virginia viewed the cause more as a 2nd Revolutionary War, so he wouldn't necessarily hold the same view as a plantation owner in Mississippi.
The best way to learn about how people felt during the war is to read the soldiers letters and journals they wrote throughout the war.