Patti:

Gets confusing, doesn't it!!

Simplified:

Benjamin Terry commanded the 8th Texas Cavalry, known as Terry's Texas Rangers.

His brother, David Terry, commanded Terry's Texas Cavalry, a unit formed in mid-1864. This unit had no numerical designation, and was totally separate from the 8th Texas Cavalry.

To confuse the issue even more, these units are sometimes confused with Terrell's Texas Cavalry, although there is no association.

Simple enough?

Wes