There was a third nation, Mayland, that seceded from the South. Mayland had no slavery. The people there were brutalized by the North. I have visited some of the caves where the people lived for years hiding from the invading Yankees.
If that's Maryland, it had slaves. New Jersey was also a slave state. Both remained in the Union, as did of course, Maryland. Delaware was a special case, with few slaves. Lincoln had a plan to buy their slaves into freedom, and use them to colonize part of Nicaragua just to show it could be done. Got turned down.
Further South, Kentucky and Missouri remained in the Union, but held onto their slaves, past the Emancipation Proclamation, which only applied to slaves in the Confederacy.
While this is all interesting history, all of the slave-holding Union States had emancipation plans, held in abeyance until after the war.
Interesting.....
First time I’ve heard about these Maryland issues.