I can see how you can think that, but there were extenuating circumstances. You see both Grant and Sherman were fighters. Grant loved Sherman and sent him through Georgia on a scorched earth policy. It was really a form of unrestricted warfare. Grant and Sherman wanted the civilian population to suffer so horribly that they would cry for surrender. Back then there were no "rules of engagement" so to speak.
When Sherman left Chattanooga to head for Atlanta there were a few skirmishes along the way. Then he laid siege to Atlanta, captured it, and burned the whole city. That's when he started his infamous march to the sea through Georgia. Their policy was to loot the homes of all valuables, steal the live stock, and burn the crops in the field. They even burned several homes. The point was that they would starve the population into submission. Sherman did this all the way through Macon and on to Savannah. He reached Savannah by Christmas. He was so taken with the beauty of the city that he ordered it not be burned. He set up his headquarters on one of the beautiful squares, and sent a message to President Lincoln. It said something like Mr. President I give you Savannah for Christmas.
Then Sherman left Savannah heading into the Carolinas with the same policy. That's when the 5th GA Cav took off after his army. So, you see many, many of the Southern troops had nothing to go home to but what was left of family.
I'm not passing judgement on if what Grant and Sherman did was wrong. They were fighters, and wanted to end the war as soon as possible. They were also amazing generals. Robert E. Lee was too much of a gentleman to do something like that, but Grant and Sherman were street fighters---not gentlemen in any way. The South did take some food to feed their troops when above the Mason-Dixon Line, but left food for the populace.
I think of Grant and Sherman in the same way of Patton. They loved the fight.
Now, let's go back to the start of the war. Lincoln had McClellan for the Union Army commander. McClellan would not fight for fear of losing. That would ruin his political aspirations. He frustrated Lincoln so badly that Lincoln wanted to fire him. Politically McClellan was the fair haired boy. He had so many political friends that Lincoln dared not fire him. The war was going badly in the East. One of the shining stars for Lincoln was Grant in the West. Grant came down to Nashville then on to Shiloh. Shiloh was a bloody battle with 10,000 casualties in one day. Grant made the South retreat for the first time. Grant went down through Mississippi and prevailed at Vicksburg. Then Lincoln fired McCellan and you know the rest of the story.
That's all well and good, but the other way to look at this is, your relative committed treason. He was a US citizen, living in the USA but fighting the government. Not a lot different than what we call "terrorists" today.
Did the north "punish the south? Yep, pretty much so. Not a lot different than if you pick a fight with someone and lose.
The war is over and has been for more than 150 years, but unfortunately, some folks are still fighting it. Not with guns, but with attitude and more subtle talk and actions.