There is so much wrong with your post I don’t know where to begin. I’ll start with this, war was never declared by congress because there was no war between two countries. There was a rebellion, or insurrection, if you will, which the constitution gives the President broad powers to suppress.
With the possible exception of Baltimore, there was no insurrection or rebellion in the states operating under Lincoln’s authority.
The war began due to the failure of the Republicans to uphold their duty to limit Lincolns actions. They allowed despotic behavior to destroy the peace.
The Civil War was not an insurrection at all. It was a separatist factional war with clear lines between the two sides. There were no partisans on either side actively warring against either government. For example Copperheads never took up arms but they were active politically and strongly anti war.