I know it's a little late, but just stumbled on this post. I'm a reporter at the local newspaper in Bay St. Louis and I'm researching this event also. All of your information is correct so far. Its unclear if the Oct. 5 skirmish and the Oct. 15 one on the tannery were the same, but an account from Acting Master Grove of the Corypheus, there was no resistance on Oct. 15. There is also a very tasty side story to the Oct. 20 engagement that nobody on here has talked about.
I discovered an article from 1942 about the local catholic church and this skirmish.
According to the report, the catholic priest named Henry LeDuc approached the union troops with cross in hand as they began burning a few homes. The priest asked to speak to the commander of the company and was granted an audience. The union troops were impressed by the courage of the priest and relented. The commander of the union troops ordered his men to mount up and leave, which they did.....The street in Bay St. Louis where this happened has forever been known since as Union Street. Fahye-1952 p9 SEC golden jubilee.
If anyone has any other information on this skirmish, please call or email me at bsldoubled@gmail.com or 228-342-2635.