The Great Southern Vampire Wars took place around the Civil War era. Mostly it consisted of various vampires who wanted large "herds" of humans to graze off of battling for control of densely populated areas by changing random people and using them as slave warriors until they outgrew their newborn strength, at which point they were killed. The GSVW eventually got so bad that the Volturi had to step in, though it is not known whether their intervention resulted in any actual action, or whether they simply had a short discussion and arrived at a diplomatic resolution.
Until now. New findings show that while the orchestrators of the Southern Vampire Wars were cunning, they did not factor on two things. Number one, the Italian Vampire Mafia. Number two, Abraham Fucking Lincoln. Both of these powerful forces headed down South, but the Volturi made the mistake of treating the sixteenth President as an edible human, while he thought of them as just another bunch of dead vampires. Finally, after half the Volturi had been slaughtered and Honest Abe had acquired quite the nasty scratch on his left forearm, the vampire leader held a truce meeting with Abraham. Negotiations went well until Aro decided to step outside, glittering dreamily in the sunlight.
Accounts differ as to what happened next, but it seems that, offended by Lincoln's hysterical laughter, Aro attacked. Abe is said to have drawn an axe from under the table, and spent the next half-hour chasing the king vampire throught the White House (whether the Benny Hill theme music played in the background is historical speculation), eventually running the sparkling monster out the doors. The following day, the Volturi were seen boarding a ship bound for Sicily.
In other words, boring and pointless backstory which causes a lot of plotholes.