What did lincolns declare was the purpose of the civil war?

He hated slavery! So he went to war to stop slavery! The North did not have slavery. But the South did! So he wanted to put a stop to the slavery!

So he could free the slaves from the South and bring back together the Union and the Confederates into one Nation.

Originally Lincoln wanted to stop slavery from spreading north into Illinois, Ohio and beyond. When the South left the Union and formed The Confederate States Of America Lincoln went to war to preserve the Union and abolish Slavery.