The South viewed their entry into the Union as voluntary and believed they had a legal right to secede when the terms were violated. The Union saw the agreement as permanently binding and treated the South differently before and after the Civil War - implying secession wasn't possible before the war but setting requirements for their return after, suggesting it did occur. This inconsistency in the North's view affected how the South was treated at different stages of the war and Reconstruction.

1. The view of the South was that the pact that they entered Union
under was voluntary. Since they felt the terms of the contract
had been violated, they surmised that they had a legal right to
separate themselves from the Union.
The Union took the position that the agreement of the original
states was forever binding. However, during and after the war
the North treated the South in two different ways: in some
occasions, the South was implied to be wayward souls, as
secession was not possible. After the war, the North set up
requirements for the South to return to the Union, which of
course implies that they left and secession did occur.
Why did the North have these two opinions? How did this affect
the way the South was treated before, during and after the war?