[Hoodat]

secessionists started the war

I seem to recall something about Federal troops crossing the Potomac River and invading the Commonwealth of Virginia. In fact, almost every battle was fought on Southern soil in defense against an invading US army. Not sure where you got this idea about secessionists starting the war. By its very definition, secessionists wanted to leave the Union - not fight for control over it.

[rockrr]

I believe that it had something to do with people taking things that didn’t belong to them.

[BroJoeK]

Hoodat: "...almost every battle was fought on Southern soil in defense against an invading US army.
Not sure where you got this idea about secessionists starting the war.
By its very definition, secessionists wanted to leave the Union - not fight for control over it."

Sure, if you believe that history began with the Battle of Big Bethel, June 10, 1861, where the first Confederate soldier was killed directly in battle, then you might suppose that Civil War didn't begin until the Union invaded the Confederacy.

But in fact, Confederates began threatening and committing acts of military aggression against Union officials from the very week of their first declaration of secession, December 20, 1860 -- seizing forts around Charleston harbor and demanding Sumter's surrender.

1. Over the next several months, Confederates continuously provoked war by seizing dozens of major Federal properties -- forts, ships, arsenals, mints, etc. -- threatening violence against Federal officials and firing on Union ships.
   Many Confederate provocations were committed in states which had not yet (or never) declared secession.

2. On April 12, 1861, the Confederacy started war by military assault on and seizure of Fort Sumter, action which resulted in two Union troop deaths.

3. On May 6, 1861 the Confederate Congress formally declared war on the United States.
   At the same time, Confederate President Davis sent military aid to pro-Confederates fighting in Union Missouri.

4. By the time of the first Confederate battle death at Big Bethel, June 10, 1861, over a dozen Union troops had died, dozens more wounded and hundreds more held as POWs.

So any claim that the Confederacy was not an existential threat against the United States is pure bunk.
Indeed, they went so far as to declare part of the Confederacy states and territories which refused, or had no legal right to declare their secession -- Missouri, Kentucky, Oklahoma, New Mexico.

And before war's end, the Confederacy had invaded or raided into every US state & territory it could reach, including: Maryland, Pennsylvania, Ohio, Indiana, Kentucky, Missouri, Kansas, Oklahoma & New Mexico territories, as well as minor insurgent attacks in California, Colorado and Vermont.

In every such invasion, Confederate forces took what they needed, sometimes "paying for", more often not, and always destroying anything reckoned as militarily valuable (i.e., railroad equipment & bridges).

That the Civil War was fought mostly in the South only reflects the Confederacy's lack of military capabilities, not their lack of will to do the Union harm.