Kevin --
You raise a couple of other important points by noticing that "Texans in the 1860s certainly weren't shy about being pro-slavery." It's uncomfortable to listen to people today who insist the war had nothing to do with slavery. As you reminded us, citizens of Texas strongly believed they had to take steps to protect themselves from attacks by anti-slavery crusaders designed to bring destruction and ruin to their state.
Frankly I find the arguments our Southern ancestors made for secession during the 1859-61 era much more persuasive than those which avoid the slavery issue that seem so popular today.