states' rights and slavery
The Confederacy was pro-slavery.
The Confederacy did not want to abolish slavery. In fact, they wanted to expand slavery into the new territories of the US.
White people in South those for slavery or states in the Confederacy.
Initially - doubts about the viability of the Confederacy. They wanted to back a winner. Ethical position over slavery - although the war was not originally about slavery, the Lancashire cotton workers said they would sacrifice their jobs, rather than support the Confederacy. Lincoln's Emancipation Proclamation made it impossible for free nations abroad to support the South without looking pro-slavery themselves. Especially good diplomatic work by Lincoln's envoy in London - C.F. Adams (of the Presidential family).
to have slavery
those who agreed with Lincoln that Slavery should not extend into the new territories.
Slavery would have never been abolished. This is because Missouri and Maryland were overwhelmingly in support of slavery.
The Confederacy was composed of states that wanted slavery. That was the main purpose of the split between the Union and the Confederacy. For that reason, it's implied that all the territories had slavery. Even if the Confederacy had allowed the people to determine whether there was slavery in their area or not, they would have chosen slavery because the vast majority of the people in the South were for slavery because it was their way of life.
The Confederacy fought the war to keep slavery
They supported the confederacy.
Supporting the Confederacy would have led to outright war with the United States. It would have also caused labor issues, since the industrial workers sympathized with the slaves and were openly opposed to slavery, and some threatened to leave their jobs rather than support the slave holding Confederacy.