@Jallenbiggs
Normally, you could find out where a soldier lived in the 1860 Census and then look at military records to see if he enlisted in a unit in that area. This Adam Biggs is complicated. I'm going by Ancestry records that others have created. He was born in North Carolina and his family and siblings lived in Kentucky, Tennessee and later Oklahoma.
This soldier in the 8th Kentucky Mounted Infantry enlisted in Breckenridge,
Tennessee , just North of Nashville. Another card in his file refers to it as Camp Breckenridge---which I assume is the same. Some of the Kentuckians did go down into Tennessee to enlist; which I think was true in early 1861 and later in mid-War when it was occupied by Union.
View attachment 318984
So I can't find a connection of this Kentucky soldier with your
Captain Adam Biggs except for your one statement that he served with General Forrest.
Fold3 also has a Confederate casualty list for Brices Crossroads. It lists
Sgt. A. Biggs with 8th Ky Cavalry wounded in the leg.
I wanted to check this just in case it might list him as an Officer; but it didn't.
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Total for 3rd Brigade
KIA= 30
WIA-Dangerously= 6
WIA-Severly= 47
WIA-Slightly= 82
Total 165