I think I can answer your question: Why did the Caldwell County recruits go to Dewitt County to join the Texas State Troops, or the Texas Rangers?
A recruiting poster or broadside dated February 11, 1862 from Dewitt County was tacked up all over that section of Texas. Frankly, it was a nice broadside that was evidently quite effective.
I do not know how to copy my page vIIpA-xxii that shows a facsimile of the referenced DeWitt County broadside onto this page, but I would be happy to forward to you if you will send me an e-mail.
P.S. My 1,014-page "Bourland in North Texas & Indian Territory During the Civil War: Fort Cobb, Fort Arbuckle & the Wichita Mountains", with a 128-page Name Index, is described on my website, www.bourlandcivilwar.com.