How did Tucson become such a lawless place before, during and after the Civil War?
When the federal army pulled out of the area in 1861-62, the Apaches interpreted the troop withdrawal as surrender and stepped up on their campaigns against the settlers. As a pueblo under siege, many residents sought safer places, heading south to Sonora or west to California.
Tucson was a pretty lawless place anyway with the vigilante activity in California chasing the bad guys into Arizona. For more on that, read Capt. John C. Cremony’s Life Among the Apaches, Capt. John Bourke’s On the Border with Crook, J. Ross Browne’s A Tour Through Arizona and Pumpelly’s Arizona by Raphael Pumpelly.