The Battle of Cotton Plant went by five different names, the other four are Bayou Cache, Round Hill, Bayou De View and Hill's Plantation. The Union troops present were the 11th wis.; 33d Ill.; 8th Ind.; 1st Mo Light Artil.; 1st Ind. Cav.; 5th and 13th Ill. Cav.
The three confederate cavalry units that I know of at the battle were the 12th, 16th and 17th Texas, with the Parson's 12th taking the lead. There may have been more confederate troops than these three involved. I think there is a new book out on the Battle of Cotton Plant, Arkansas, but I'm not sure. Also on the Arkansas Civil War Message Board a discussion on the Battle of Cotton Plant was held awhile back, if I remember right.
You might try and find that discussion on the Arkansas Message Board Archive or make a new post there.
I made an error in my last post about the Missouri soldier's journal ( that's what you get when you go from memory). He called the camp west of Austin, Camp #3 and he may have been talking about a camp that was a few miles further west on the Batesville Road. The date in his journal was June 1863, so this was at least six months past Camp Nelson's heyday. But their 1863 camp west of Austin was at the same location as the 1862 camp.