What happened after Sherman's March?

Answer 1

Grant wanted him to ship his army to Virginia to join forces with him at the Siege of Petersburg.

Sherman preferred to cross the river into South Carolina (the state that had started the war), destroy the small Confederate army that had eluded him in Savannah, and continue his campaign of devastation of farms and railroads.

Fortunately, Sherman carried high credibility with Grant (who had initially been sceptical about the March to the Sea), and he was allowed to go his own way. It is doubtful whether the war would have ended any quicker if all the troops had gone to Petersburg.