Why was the march to the sea important to Sherman?

Answer 1

It put him on the map - not always very flatteringly!

Up to then, his reputation had not been especially outstanding. He was known mainly as a close colleague and supporter of U.S. Grant, and his pursuit of the Army of Tennessee had been only a qualified success.

The March to the Sea was an entirely new strategy, which neither Grant nor Lincoln was ready to endorse at first. Sherman himself was privately jittery about it - if it failed, he would lose all credibility.

But in fact, it turned out a stunning success, shortening the war by months, at almost nil casualties. The plundered and starved civilians of Georgia and South Carolina might take his name in vain. But in US history, he is up there alongside Grant as the victor of the Civil War, and (indirectly) the liberator of slaves.

Answer 2

it killed a lot of people

Answer 3

It helped get Lincoln reelected.