Roster of Confederate Soldiers, 1861-1865 shows:

Dyer, C.L. TN 2nd (Ashby's) Cav. Co.D
Dyer, George TN 2nd (Ashby's) Cav. Co.B
Dyer, Isaac TN 2nd (Ashby's) Cav. Co.D
Dyer, J.J. TN 2nd (Ashby's) Cav. Co.F
Dyer, James TN 2nd (Ashby's) Cav. Co.B
Dyer, John TN 2nd (Ashby's) Cav. Co.B
Dyer, Waaren B. TN 2nd (Ashby's) Cav. Co.D

TN 2nd [Ashby's] Cav Reg
aka: TN 1st Cav Reg [until Dec 1862]
Organized by Consolidation of 4th & 5th Cav Batt'ns 5/24/1862 - surrendered by Gen Joseph E. Johnston at Durham Station, NC 4/26/1865
First Commander: Col. Henry M. Ashby

suggested reading: Hancock, Richard R., Hancock's Diary

see also, A Compendium of the Confederate Armies - Tennessee, by Stewart Sifakis