 Detached from the division in 1863, the 4th brigade fought at the Battle of Arkansas Post, where it became isolated and was forced to surrender.A new 4th brigade was added the division in 1865.Among the most famous mounted units were Terry's Texas Rangers, a militia of former rangers and frontiersmen, many of whom later became peacekeepers in the Old West; and the 33rd Texas Cavalry Regiment of Colonel Santos Benavides, which guarded the Confederate cotton trade lines from Texas into northern Mexico.