As Virgil noted in his post there were two men by the name of John Travis with ties to Amite County, one being the father of Nicholas Travis. The other John Travis was married to Mary Raborn/Rayborn and had a son named Henry, born circa 1844 in Amite County. This family moved from Amite County to Anderson County, Texas between the 1850 & 1860 census.

I'm fairly certain the Henry Travis of CO H /4th. Texas Inf. was the son of John & Mary (Raborn/Rayborn) Travis. He was enlisted by this man http://www.granburystexasbrigade.org/gallery/heroes/officers/hunter_james.html in Anderson County, TX.

This Henry Travis was in camp near the Potomac River and did serve at Chickamauga, he was later killed in action at the Wilderness and buried here.
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=travis&GSfn=h&GSbyrel=in&GSdyrel=in&GSst=48&GScntry=4&GSob=n&GRid=10930163&

This excerpt from George S. Lea's letter from Chattanooga dated 10 Oct 1863 to his father does seem odd unless he was referring to John, the father of Nicholas Travis.

"You can tell John I seen Henry Travis a few days ago. He is in fine health and probably will remain with this Army and not go back to Virginia any more."