This order may explain why certain units were left out of the organization of a 1st corp and not organized as a 2nd Corp.
LITTLE ROCK, ARK., November 1, 1862.
General T. C. HINDMAN, Commanding First Corps:
MY DEAR GENERAL: Your affairs seem to have gone terribly wrong, your juniors taking to drink at the time they were most wanted. I cannot think the enemy will attack Fort Smith until they have beaten you, but I have directed the troops at Austin to be ready to move it they are necessary to you. I must leave the lower Arkansas very weak, though I do not think the enemy will attempt to advance from Helena unless they are re-enforced. Magruder has been ordered to Texas and Frost and Hebert here. I will send you Fagan in a few days. I will probably send you 2,500 more arms in two days, as I am told that number is near here. It may be I will send 3,000 to complete the arming of your unarmed men. Allen has a fine regiment, well drilled, which must be armed. Order the couriers to be placed as is best to communicate between you and myself, and give such orders as may be necessary for the subsistence of your command. I will come up as soon as it is certain that you will want the forces at Austin.
I am, general, yours, very truly,
THE. H. HOLMES,
(OR's Series 1, part 2, Vol 13, page 907)
It would seem that besides not being armed in some cases such as Allen Texans. They also constituted the only reserves which were available.