I feel that the subs would probably have been on a one-way mission down the Red River, if they had ever been deployed. Depending on the level of the Red, coming upstream would have been impossible. I believe the Hunley sustained around four knots. After a good rain, the river would have been moving that fast, if not faster.

The subs were equipped with a spar torpedo and a towed torpedo. Attacking with a spar torpedo going downstream with a good current would probably have been disasterous for both vessels involved.

It appears that the subs were made from steam boilers, like the Hunley, and only varied by having a lone, front conning tower. Shreveport, at the time, was a major steamboat port for northwest Louisiana, and a stopping point by water on into Texas, to the town of Jefferson, Texas, which was the second biggest town in Texas, due to its water route access to the Mississippi. It is understandable that riverboat steam boilers would have been readily available in the area.

Looking at the time line of events, the Hunley was lost February 17, 1864. We all know the sinking of the Housatonic sent shockwaves through the Union and Union Navy. The Singer Submarine Corps left Charleston and set up shop in Shreveport, and started building new subs. How many were actually built by the time Porter brought his fleet up the Red in April, 1864, we can never know (the fleet was the largest assembled naval fleet in the history of the United States, having almost 100 vessels). But, it appears that enough was done to give the perception of a real danger to the Union fleet. It also appears that, through disinformation, Porter was told that there were two, possibly three, operational ironclads in Shreveport, while actually there was only the CSS Missouri.

As for the practicality of the subs in combat, we'll never know. It must be remembered that the Union Navy was terrified by the existence of Confederate submarines, and the mere knowledge of their existance was a very real threat that had to be taken into account by the Union Navy, while planning their attack methods.

The Union Army, being transported by Porter's Naval fleet, suffered a humiliating defeat at the Battle of Mansfield, and the Battle of Pleasant Hill, south of Shreveport. The dynamiting of a levee on the Red River at Tone's Bayou, south of Shreveport, caused the Red River to divert into Bayou Pierre, and the water level of the Red dropped too low for navigation. The Union advance on Shreveport ended, and Shreveport was never threatened again. In the end, had all of that not happened, and Shreveport had been engaged by river, there is no way what was here could have withstood a fleet of that size. Still, I'm sure a "showing" would have been made...