From The Alexander Papers and The Official Records:

6/3/62 Gen Order 6- the forces in this district are organized as follows:
...
Gen Roan is assigned to the command of the forces at and near Little Rock

6/12/62 G O 16 TM Dist Gen Roan is relieved of command of “Roan’s Bgde’ in the “Army of the South West” and is assigned to the command of the Ouachita district of the counties of Chicot Ashley, Drew and part of Desha south of Arkansas River and parishes [named] in state of La -Col Nelson will assume command of “Roan’s Bgde

6/15/62 Special Orders 5 Army of the South West
...
Col F Shoup will assume command of Col Pleasant’s “1st Trans Miss Inf” Daniels’ Lamar Arty and Hart’s company of Arty [with the heavy arty] and move tomorrow to Devall’s Bluff. If Col Nelson is not there Col Shoup to assume command-If Nelson is there Col Shoup will report to him as second in command

6/16/62 Hindman to Col Shoup, St Charles-Col Nelson will be at Devall’s Bluff tomorrow evening- besides his regt of Infy he has a small force of Cav not yet large enough to do any good-I have ordered Wheat’s company to him...

Official Records Vol XIII
Hindman’s report… Several days before this battle [St Charles on 6/17] Col (afterward Gen) Nelson, now deceased, a most excellent officer, arrived at Little Rock from Texas with his well-armed and finely-disciplined Regt of Inf. He was ordered to Saint Charles in ample time to have reached there before its fall, but, being without ammunition, was detained at Devall's Bluff until I had succeeded in begging, buying, and impressing enough for 40 rounds, making it into cartridges and sending it to him by rail. He then started down the river by steamer, and was within 15 miles of Saint Charles when it fell. Appraised of that event, he returned to Devall's Bluff, where entrenchments were thrown up and three heavy guns from the Pontchartrain put in position. Obstructions were also put in the channel to detain the enemy's vessels under fire. A Regt and battalion of Arkansas Inf, just organized and armed party with shot-guns, sporting rifles, and partly with pikes and lances, were sent to Devall's Bluff, together with three btrys of Arty, and, with the Regt already there, were formed into a Bgde under Col Nelson.

6/21/62 Hindman to Col Nelson-send Col Shoup back here and you assume command of the force at Devall’s Bluff and of 18th Tx Cav when it arrives, and proceed at once to organized them into a Bgde which will therefore be composed of:
Nelson’s Tx Infy 10th Tex Inf
1st TM Inf [Col Pleasants’ Ark regt]
Morgan’s Ark Inf Bn
Darnell’s Tex Cav 18th Tex Cav
Wheat’s Ark Cav Co
Clay’s Ark Cav Co
Daniel’s Btry