Chase,
Over the last few years I have been supplementing my research with the CSR's at Fold3. A tedious examination of each man in each unit of interest has yielded many clues for me.

Even better has been the study of Confederate Records [RG 109] from the National Archives. They have digitized over 2700 of these records so far.

It is my best guess that the information you asked about came from one of those sources. I will try and examine them when I get the chance, but I have accumulated a vast amount of notes; including for Dockery's exchanged brigade.

Here are some more related comments regarding Dockery's exchanged brigade serving as infantry:

12/3/63 Confidential-K Smith to Holmes: Your letter of 12/2 is received. I leave immediately for Alexandria, & expect to return Tues next. A personal interview with Gen Taylor regarding the movement of reinforcements from La to Tex necessarily takes me to Alexandria. On my return I will proceed immediately to your Hqs. In the mean time make all your arrangements & dispositions for carrying out the plan of operations you may adopt. The question of supplies & transportation will be the greatest difficulty to be encountered. I know not what your resources are, nor whether you can calculate upon rapidly accumulating the necessary supplies in the country you may advance in

If a move on Pine Bluff is determined upon, I think the force under McCray could be made a valuable auxiliary. He should be prepared in advance, &, acting in connection with even a small Bgde of Cav sent north of the Ark, could operate on the enemy's communications, engage his attention north of the Ark, & create a favorable diversion for the expedition.

Efficient officers or agents should be sent into Eastern Ark, & supplies should be collected on the route between Pine Bluff & the Washita River, via Monticello. Arrangements should also be made for the safe & expeditious crossing of the Washita by your command below the mouth of the Saline. You may be compelled to take this line in falling back, either from the flooding of the streams or the overpowering numbers of the enemy. Steamboats should be collected at the point you propose re-crossing the Washita, & if a temporary bridge could be constructed with these boats it would be advisable

I am expecting daily the arrival of 1200 Enfield rifles, now en route from Navasota to this point. They will be immediately pushed on to your command. Gen Dockery's men should be first armed, & his command will be placed at your disposal as Infy. The remainder of the arms can be disposed of as may be most advisable.

12/5/63 to Col Dockery cdg Bgde-The Lt-Gen cdg directs me to say it is his purpose to put your command into active service immediately. He directs that you quietly, but promptly, draw in & prepare for the field all the men of your command within your reach. Arms will be immediately sent to Gen Holmes, with which your command will be first supplied.

The Lt-Gen instructs me to say, further, that the whole of your command will serve as Infy even should a portion of it have been Mtd. He desires all your preparations made with the utmost dispatch, but without attracting attention.

2/22/64 Smith to Dockery-report by letter to Gen Holmes & also send to these Hqs a report of the strength of your command

2/23/64 Smith to Holmes-Dockery has been ordered to write to you. As soon as he is finished with the special duty assigned to him he will be returned to you & I desire that you then dismount his command in the manner least calculated to cause dissatisfaction

3/10/64 Smith to Holmes-Rec’d yours of 3/5 regarding the dismounting of Dockery’s command that in his opinion it will be best to allow the men to dispose of the horses. If necessary they may be impressed afterwards. Up to you as to sending Col Brooks to NW Ark

3/22/64 Smith to Price-...with your 4 Bgdes of Cav & Dockery's & Fagan's Infy your command should approach 7000 men

Number of Prisoners, by unit, from Longview
By: Damon Cluck Date: 6/16/2016, 6:44 pm
Anthony Rushing helped me answer an old question about presence of members of Dockery's Bgde of Paroled & Exchanged Prisoners from Vicksburg & Port Hudson at Longview on 29 March 1864.
In almost every letter of the Alphabet, there is a list of Prisoners captured on March 29, 1864, at Longview in Ashley County. I have listed the unit & the number of Prisoners from that unit below:
Woods Mo Cav............................................40
1st Ark Cav................................................99
2nd Ark Cav...............................................38
9th Ark Mtd Infy (suspect 19th)..............1
10th Ark (aka 10th Ark Mtd Infy)....12
11th Ark (aka 11th Ark Mtd Infy).....14
12th Ark (aka 11th Ark Mtd Infy).....6
15th Ark (aka 15th Ark Mtd Infy)....17
16th Ark (aka 16th Ark Mtd Infy).....6
18th (aka 18th Ark Mtd Infy)...................6
19th (aka 19th Ark Mtd Infy).................16
20th Ark...........................................................4
21st Ark............................................................2
23rd Ark...........................................................2
24th Texas Cav.........................................................3
3rd Trans Miss Infy......................................3
Wright's Ark Cav..............................................24
Fagan's Div.........................................................1
Dockery's Bgde.......................................................1
2nd Mo Cav........................................................2
Glenn's.....................................................................1
Clarks'......................................................................1
Shanks Mo Cav...................................................1
1st Trans Miss Cav.............................................1
Woodruff's Bn....................................................1
Conscript...................................................................1
5th Infy (suspect 15th?)........................................1
..............................................Total........................304
There are some obvious errors, but I have listed the units as described in the Register. The only Vicksburg or Port Hudson units that I didn't see were Power's 14th Ark, 8th Ark Bn

4/26 Hqs Dockery’s Bgde-Camp Buena Vista-Capt Poyner 16th Ark tenders resignation-appd H G P Williams cdg Infy Bgde [of Dockery’s Bgde] appd Churchill Div

Extracts from the Memoirs of William Franklin Avera, ARK HISTORICAL QUARTERLY, Volume 22 (Winter 1963), p. 99 http://peace.saumag.edu/swark/articles/ahq/camden_expedition/avera/avera99.html
Brought to Camden, by his parents when he was two years old. With the exception of the war years, he grew up & spent his life in Ouachita County. At the age of sixteen, he joined the 5th Ark Arty Co, & served for the duration of the war...
At the time Gen Steele’s Army was coming down from Little Rock in the direction of Shreveport & Gen Banks was coming up the Red River. It was a lively time with our army. We had to meet them with very inferior forces. The Cav was sent to meet Gen Steele which they did, first at Arkadelphia. While all the Infy was sent to meet Banks. Our company was at Lewisville & had no guns. Our cannon had been given to another company & we were to have a new outfit but they had not yet come. An order had been made sometime before to mount our Bgde. Dockery’s & about half the men had procured horses & was with Gen Dockery’s & the Cav. The rest were with us, with Col H. G. P. Williams in command. One of our company, George Robinson, & me took a fool notion that we would join the Cav, though the order did not apply to us. To do this we had to go home to get horses. I had a horse at home & we thought we could find one for Robinson

4/30 Jenkins Ferry battle-H G. P. Williams-Lt Col Cdg Infy [Portion] Dockery's Brig

Bryan’s post-The dismtd casuals of Dockery's Bgde had been formed in to a Regt of 4 Co’s under Lt Col H. G. P. Williams’ command attached to Churchill's Div
15th Ark Infy, under Capt Austin K. Etris
18th Ark Infy, under Maj Samuel H. Southerland
19th Ark Infy, under Capt Thomas M. Drewry
12th Ark Bn, under 1st Lt James A. Gillespie

Williams' command was attached to Fagan's Cav Div.

Williams reported: I carried into action nearly 400 men, divided into 4 small dtchmts, under Capt’s Drewry & Etris, Maj Southerland, & Lt Gillespie, composing the Infy portion of Gen Dockery's Bgde.

5/7/64 # 64 Report of Lt Col H. G. P. Williams, 19th Ark Infy, Dockery's Bgde, of engagement at Jenkins' Ferry-
Camp near Camden- requiring a report of the action of my command in the battle of Jenkins' Ferry I have the honor to submit the following: I carried into action nearly 400 men, divided into 4 small detachments, commanded respectively by Capt’s Drewry & Etris, Major Southerland, & Lt Gillespie, composing the Infy portion of Brig-Gen Dockery's Bgde.