The war waged on the south was total war. It was waged against military and civilians alike. Livestock was slaughtered, wells poisoned, homes ransacked. The goal of the war was to break the south, break their will, break their character. Sherman's March to the sea incinerated whatever was left. The burning of Atlanta was a lesson in how inhuman mankind could be to itself.
The most important thing to the north was that this never happens again. To find a provision passed without being used isn't surprising.