I'm a bit confused by your original posting that stated that Williamson Sellers died at the battle of Mansfield, La. in April of 1864. If Sellers served with the 17th Cavalry he should have been in Georgia at that time. The 17th Dismounted Cavalry was captured at the Battle of Arkansas Post in Jan. of 1863. After they were exchanged, they were consolidated with other captured units to form the 17th-18th-24th-25th Regiment Texas Cavalry(dismounted). They were in Granbury's Brigade and fought at Chickamauga, Chattanooga, Atlanta Campaign, Franklin and Nashville Tenn. and Bentonville N.C. After the exchange this unit never served west of the Mississippi. Google Granbury's Brigade for more info.