Why did William Tecumseh Sherman invade Georgia?

Sherman invaded Georgia, with the "March to the Sea" campaign in order to end the war. He, as well as him men and the Union (U.S.A), were sick of the war and knew that the South would go on forever, for they had almost infinitely amount of people to throw into battle (slaves). He did so because the war needed to end, and if he didn't, then the war would have maybe lasted another 10 years.