Large numbers of the original regiments were NOT present, due to being absent for illness, or on other assignments, when "The Post" fell. Or excaped during the confussion. For example there was a 19th and 24th Arkansas Infantry Consoildated in the A.O.T., and a 19th and 24th Arkansas Infantry Consolidated, commonly called Hardy's Regiment, in the Trans-Miss. "Officially" both units were addressed as the 19th and 24th Arkansas, in tables of organization, in both theaters.
That has been the source of many misunderstandings in researching the men of those particular units. There is a large discrepency about the "actual" number of men "captured" at Arkansas Post, but upwards to maybe 1,000 men who were "on Paper" to be at Arkansas Post, were either not there, or excaped. We know that at least one regiments of 300 to 400 men belonging to the 19th and 24th Arkansas were NOT there. And that at least 200 of these mounted cavalry were able to also excape, maybe even more, because they were posted on the flanks.
The same thing happened with mounted Cavalry Alf Johnsons's Texas Spy Company, Richardson' Cavalry, Nutt's and Denson's Louisiana Cavalry, who excaped. A large number of the mounted Cavalry at Arkansas Post excaped throught the swamps. Most of the Texas cavalry that remained in Arkansas, became part of Morgan's Texas Cavalry regiment. A lot of Nutt's and I believe Denson's men found their way into the 6th Louisiana Cavalry.
The Trans-Miss commanders fully expected these unit to be returned to that theater by the normal exchange process, and those units to be reunited. But when they were exchanged at City Point rather than in the Trans-Miss. that upset the game plans. It was impossible to effectively return and reunite these regiments.