Lindsley's Annals, Military Annals of Tennessee, records on page 260, a 2nd Lt. W. C. Knox, Co. F,
Co. F was raised in Wilson County.
This work, published ca 1881 does not list him in the regimental roll of honor of CW dececeased. This does not mean however, that he survived the war as they are imperfect records.
Tennesseans in the Civil War list a William C., Bvt. 2nd Lt, Co. B , 4th [Starnes] Tenn. Cav. Co. B, likewise, was raised in Wilson Co. Bvt. 2nd Lt. would be the same as 3rd Lt.
Good hunting,
George Martin