Hi Lars -
Am at work now, but pretty sure that R.C. Newton's 10th Arkansas Cavalry (along with my great-grandpa Joe Bishop) were under Brooks at that time.
They seemed to harass not only Federal fortifications like at Dardanelle, along the Arkansas River, but also Federal gunboats and steamers as well during 1864-1865.
If you don't have it already, here is the Cornell University O.R. search site:
http://moa.cit.cornell.edu/moa/browse.monographs/waro.html
You should find a fair amount of info on Brooks and his activities during 1864-1865 there.
best wishes,
Kenneth Byrd