Sorry, I do not know if the map is in the Atlas to the OR's, but can tell you to look for a pink granite Texas monument near the hurricane museum close to the water in Galveston. The monument was placed a just a few years ago and is in the style of the Texas Monuments placed at major Civil War battlefields.

I am a US History teacher at Tomball High School and my students are required to research veterans buried in/around Tomball. Most of the men from what is now Tomball were in the 20th Texas Infantry/Elmore's Regt and saw action in the recapture of Galveston, hence my knowledge.

I hope you will obtain the map, because even though the topography has been somewhat altered you will still be able to guess closely where places were located.

Best wishes,
William Bozic