Jacob Rau was in Co. E 8th Provisional Enrolled Missouri Militia. His service card on the Missouri State Archives military database has him formerly in Co. B 56th Enrolled Missouri Militia. I am currently researching the 8th Provisional but not this man in particular. The Official Records has a couple battle accounts that include the 8th in Arkansas but again names of those in the 8th are not mentioned. Generally the 8th was on scouts with other Mo. volunteer (not EMM or Prov. EMM) detachments commanded not by Provisional officers. Consequently, the reports emphasize and praise the Mo. volunteers and make no mention of the Provisional Militia. There could be a pension file on Rau as only those in the Provisional Regiments could receive (as compared with the Provisional Enrolled Militia and the Enrolled Missouri Militia). Through much digging you may find some background on the 8th Provisional but no mention of Rau.