What event triggered the war between the union and the confederacy

I think its was because of Lincoln's rejection of the Final Compromise.
(Extension of Slavery)

Ifound this on google “simply, the working conditions were terrible during the industrial revolution. as factories were being built, businesses were in need of workers. with a long line of people willing to work, employers could set wages as low as they wanted because people were willing to do work as long as they got paid.” i hope this you for what your looking for.