Well, I'm sorry to mystify you on this :)

I went back to my records and took another look at the enlistment paper. It is dated Oct 6, 1862 and the enlistemnt was into Co. B22 Regiment of the St. Louis County Enrolled Missouri Militia. The back side of the card has vital stats with his age listed as 21.

To further the mystery is a handwritten transcription from an unknown source that states:

"Mark Fortune

HD. QRS. Military
Harbor Master

St. Louis, Oct 4, 1864

The guards of this city will pass Mark Fortune until further orders by Command of Maj. General W.S. Rosecrane(?), Command Department of the MO Gen. W. Ford.

Military Harbor Master"

A cryptic note at best, but interesting none the less. I can't make out the handwriting on "Rosecrane" for sure, but that is what it looks like. I'm not sure if this sheds any light on things?