#1) The Confederate States had ceceded from the Union, wrote a constitution and sent diplomats abroad.
#2) The North invaded the South.
#3) The Federal Army had whole units of immigrants who did not speak English. If you had a bunch of Germans marching through your town...you would think them as foreign invaders.
#4) When a confederate POW was asked by a Union officer, “ Why are you fighting this war soldier?” The confederate answered, “Because your down here.”
So the confederate soldier felt they were defending their nation.
Hyde-Smith pushed resolution praising Confederate soldier's effort to 'defend his homeland' - CNNPolitics
If the South wanted to be left alone, why did they start the war by firing on a U.S. Federal installation that was doing nothing to them?
See the Nullification Crisis 1832. Lincoln had already stated that secession would not be allowed. Andrew Jackson asked for a force bill in 1832 so the South could expect said same. Also, the South was not being left alone. Northern members of Congress, in order to protect wealthy industrialist, had pushed for tariffs that would have been detrimental to southern planters.
Not really. The south was concerned that the balance of power in the US Senate was about to be turned against them as the country moved westward and each new territory and freshly minted State was taking the anti-slavery route. Until that point, the South had always had a balanced number in the Senate to counter the efforts of the north to do away with slavery. It was a stalemate the wanted to turn to their own advantage and when the raids in Kansas started, it was only a matter of time before the South decided to go to war.
Most people understood that the entire economy of the south was predicated on agriculture and depended upon slave labor and the efforts of the north to remove the right of states to hold slaves likely seemed like an act of aggression, but it was not. It was simply the right of free men exercising their liberty and the south did not like it.
They should have tried harder to come to a reasonable compromise. Secession was not a reasonable response.