Does the memoir of a trooper belonging to the Thirteenth Illinois Cavalry, "Three years in the saddle from 1861 to 1865: memoirs of Charles D. Field," (published 1898) not offer any clues? If you haven't checked, and don't have access to a copy, I'll see about digging up my copy and check if it reveals anything. I had pretty good luck utilizing it to shed light on other escapades tied to Hildebrand.