There is a report written by General Powell Clayton in volume 41, part 3, correspondence, regarding the patrol sent ouf from Pine Bluff under the command of Colonel Albert Erskine to Monticello on September 9th, 1864. After driving in the Confederate pickets the Federals retreated. They were pursued by a detachment of Parson's Texas cavalry in which some casualties occured. Clayton's report mentions a prisoner captured during the affair that stated he was with Lane's cavalry just in from Louisiana. Perhaps your ancestor was with Parson's Texas cavalry and not with Isaac F. Harrisons cavalry which did not arrive at Monticello until mid September along with Walker's Texas Division and Polignac's Texas/Louisiana Division.