Answer:
To break the will of the Confederacy's citizens.
Step-by-step explanation:
General Sherman's "March to the Sea" was a march of a fighting force of around 60,000 men, going from Atlanta to Savannah, Georgia (a distance of 285 miles). It was intended as a show of force, to intimidate. They did not burn everything in sight, but did burn the houses and barns of any people who tried to resist them or fight back.
In addition to intimidation, Sherman also believed that the destruction caused by his march would effectively divide the South in two. Sherman felt that by marching from Atlanta to the ocean he could create a zone that would cut a hole through the heart of Confederate territory.