To follow that up the NY Times contemporary story refers to him as Mr. Ben Lewis. This would indicate to me the title Colonel was bestowed after the event and/or war. Perhaps an honorific given for his Union sympathies even though he was well endowed "southern tobacco planter" with upwards of 100 slaves in 1860.

https://www.nytimes.com/1864/11/20/archives/the-war-in-missouri-horrible-chapter-of-guerrilla-atrocities-a.html

JJR