Comments;
Yes, i would think the the Prisoners from Fort Donelson and Island # 10 were the first big wave of Prisoners that had been Paroled and were sent to Vicksburg for exchange, however, I would think there were Prisoners before and were certainly Prisoners afterward.

Also, the Prisoners on the Sultana were the first big wave of Yankee Prisoners sent to Vicksburg as the end was approaching (1865)

There were many more after the Sultana.

There were a number of Confederate Prisoners sent from Ship Island and the Mobile area to Vicksburg near the end. This causes much confusion

Also, the Location of Camp Fiske and the Four mile bridge.
Four miles Eastward from the End of Track I would suspose,
Perhaps a mile Eastward from the Point the Rail Road passes through the V N M P.
Perhaps a half mile Westwrd from the point where Mississippi State Highway # 27 crosses the Rail Road.

It is a huge creek that flows through Warren Central High School.
When we get the big rains (Sometime 8 - 10 12 inches in a single night.)
A tremendous amount of water comes down this creek.
Thus the very high rail road bridge.

Sam P