Sherman's "March to the Sea" occurred after his successful Atlanta Campaign of May-September 1864. Sherman and Ulysses S. Grant, both powerful leaders in the Union decided that the Civil War would come to an halt only if the Confederacy's strategic, economic, and psychological capacity for warfare were undeniably broken. The march was planned to be a full 300 miles, as it was executed.
Why was the battle significant?
Sherman's general strategy that he implemented in his warfare strategies are called scorched earth, or total warfare in today's standards. The original idea was to value control of the region over the destruction of the region, but destruction of the territory was afar more apparent result the the Union's march. The march had crushing effects on the Confederate's morale, therefore being a factor of the south's loss of the Civil War.
Result of the battle
The march ultimately crushed the south's morale. Miles and miles of destruction from the Union soldiers was left behind, not to mention the Union soldiers looting valuable items from the southerners. The north ultimately left behind 300 miles of pure anarchy and destruction in the south. It also defined that the Union was the more powerful force in the Civil War, by showing no mercy and brutal destruction. The March also set a clear message to the south, which was that the Union was the more powerful force in the war.