Texas was a backwater in the ACW. Especially west Texas. The best troops had been sent east with Hood and Robertson, et al., and there were few strategic objectives to be had.
The capture of Fort (Jefferson) Davis in August 1862 had great symbolic value, however, even though it was just a few, mostly ramshackle adobe buildings.
As you could see in the previous post with the OR citations, the Union and rebel forces were somewhat more concerned about the Indians than each other, and when the rebel POWs were paroled to San Antonio, they were escorted for their own safety.
Your story about the confederates abandoning the Rio Grande forts "for lack of any need" not jibe with leaving their sick and wounded behind. Those, from several outposts, numbered over 100. It sounds to me like the able-bodied Texans quickly skedaddled.
Here's what the Handbook of Texas says about Fort Davis (which was NOT named for Davis as president of the CSA, but rather because it was established by Secretary of War Jefferson Davis in 1854):
With the beginning of the Civil War, United States troops evacuated Fort Davis under orders from Brig. Gen. David E. Twiggs, commander of the Eighth United States Military District, and were quickly replaced by Col. John R. Baylor's Confederate cavalry forces in April 1861. Confederate troops occupied the post for almost a year, then retreated to San Antonio after failing to take New Mexico. For the next five years Fort Davis lay abandoned, and Indians used the wood from its buildings for fuel.
It did not see military use again until 1867 and, as the National Park Service's records indicate, no military officer on either side so much as set foot there between 1862 when confederate Lt. W.P. White returned to San Antonio and July of 1867 when the federal calvalry showed up to fight the indians. Another site tells us the following:
A Federal cavalry detachment visited Fort Davis in August, 1862, found most of the buildings in disrepair, and left the next day. The remains of the post lay empty for the next five years. (http://www.texasbeyondhistory.net/forts/davis/camp.html)
Ah, the "capture" of Fort Davis in 1862. That must've been some symbolism, I tell you what! I mean, imagine the shock on those non-existant confederate defender's faces when they learned that a couple of yankees on horseback stumbled upon the Apache bonfire yard that used to be Fort Davis! And to think - they even spent a night amidst the rubble...absolutely crushing to CSA morale, no doubt! Of course this all leaves us with another question: where exactly did you get your information the Battle of Fort Davis, aka the weenie roast at the Apache wood pile, in August of 1862? Oh, that's right. You got it where you get all your information, especially for court cases and other "official" records: you pulled it out of your @$$.
Your story about the confederates abandoning the Rio Grande forts "for lack of any need" not jibe with leaving their sick and wounded behind.
Garbage. They left the wounded behind because El Paso was the only town of any size in the area, and even it had a population of only 200 civilians in the 1860's. Marching wounded soldiers across 500 miles of Texas desert in the middle of August would've been a death sentence, so instead you leave them in town till they heal and till the whether is a little less harsh.