ASB but the image of Sherman riding an massive war elephant into Richmond at the head of a column of elephant towed artillery and proud Federal troops is just to awesome for me to not think about.
Unfortuneately they where offered as pack animals, which is so non-creative that it requires real imagination to come up with. I mean come on, the confederates would have surrendereed to an oncoming charge of elephants in no time!
War elephants in an age of artillery aren't really that useful--they panic and trash their own side, among other things.
However, for small-unit type stuff in which there wouldn't be much artillery, they might come in handy. Plus I get the impression elephants scare horses--one reason the Mongols ran into trouble in SE Asia.
Hmm...send them to places vulnerable to raiders like Quantrill?