The death of Lincoln also allowed people who wanted retribution against the south to gain power.
That's a myth from Democrat history books. The reason Confederates were worried when Lincoln was shot was that the Vice President, Andrew Johnson, had been vowing to hang the rebel leadership if he were President. Once in office, however, he quickly reconciled with his fellow Democrats.
In contrast, the Republican leadership at the time -- Stevens, Sumner, Trumbill, etc. -- were, for example, opposed to the death penalty for all cases, including sedition/treason. Far from wanting vengeance, they wanted the slave system completely uprooted. Most southern whites could not even vote prior to Republican Reconstruction.
The South lost the War..remember? It's always good to be on the winning side... All things considered, they ended up in much better shape than if, say, they were part of Europe, for example.