Mike, glad to help. A couple of minor corrections. The service record tells us that Lyell escaped from Fort Donelson, so he was not among those who received an all-expense paid vacation to prison camp in Chicago. For all he knew, the regiment no longer existed, and Lyell evidently wanted to continue the struggle. That would explain his enlistment while most of the 42nd Tennessee was still imprisoned.

Also, it seems to me that Blackman's name was simply misheard. Blackburn was spelled correctly -- just the wrong name.

You may want to run some searches on the name 'Dick' McCann. The Yankees regarded him and his men as guerillas --
http://tennessee.civilwarsourcebook.com/collection/1862-09/1862-09-Article-142-Page189.pdf