Sherman's capture of Atlanta was politically important as it convinced many people in the North that the war would soon end, and in fact aided in the re-election of Abraham Lincoln. Up to that point, Lincoln's re-election had been questionable. He was only re-nominated on the ninth ballot and was opposed on the Democratic ticket by George B. McClellan, the former commander of the Union Army whom Lincoln had fired. McClellan was supported by northern Copperheads, that is Democrats who wanted an immediate end to the war.
Atlanta was one of the major industrial cities in the South, and its loss was a devastating blow to the Southern cause. Sherman turned it into a fortress and forced its residents to leave. He ordered his troops to destroy major factories and railroad lines by setting them on fire; but the fire burned out of control and destroyed over one third of the city.
Sherman used his victory at Atlanta to convince Lincoln and U.S. Grant, now commander in chief of Union forces, that he should wage "total war," in order to break the spirit of the Southern people. On the strength of this, he began his famous "March to the Sea" in which he destroyed immense amounts of Confederate property and crops. His efforts led the South to believe the war was no longer worth fighting.