This is from the TenGen Web "Tennesseans in the Civil War" -
"As is well known, Colonel Forrest refused to surrender at Fort Donelson and led his force out through the backwaters of the Cumberland River, although two companies remained in the fort and surrendered. These were Captain Gould's Company "D" and Captain Davis' Company "I Neither of these companies again served with the regiment."
According to one of the service cards of one of the officers mentioned above - Company K the 23rd Texas Cavalry (aka 27th) previously served as Company D of Forrest's 3rd Tennessee Cavalry.
John Walsh