This cover was sent from George Taylor Banks in Warren, Ohio to J. K. Wing in Corinth, MS dated
06/21/1963 05/21/1863. While there are still some things to learn about this cover, I thought I would share some of the things I have learned this far. Please feel free to further fill in the story of this cover.
Front:

Back:

The notes on the post-it note were written by the seller, a friend of mine.
The addressee was J. K. Wing who was most likely at the time Lieutenant of the 4th Iowa Volunteers under the command of General Greenville M. Dodge stationed in Corinth Mississippi.
Here is a picture of some of the detachment while in Corinth including Mr. Wing (red arrow).

Another interesting aspect of this cover is the transit or received cancel on the back.
A study of the main shipping channels reveals that Warren, OH is not far from the beginning of the navigable portion of the Ohio River. The cover would have been transported most likely to Pittsburgh, PA (or perhaps Liverpool, OH) and then traveled down the Ohio to the Mississippi River.
Cairo, IL sits at the confluence of the Ohio and Mississippi rivers. Most likely it was a central mail processing point for traffic on the Mississippi, Missouri and Ohio rivers.
In case you were wondering, the practice of placing received cancels on the backs of envelopes did not begin until 1879.