Hello /r/askhistorians, I am back again in much more dire need of help regarding the question above.
I've posted this before (see quoted text below) in hopes of answering a very narrow question. I've approached my teacher to tweak the question, looking more into the wars in the entirety of the industrial revolution of the United States (early to mid 19th century) than just a single war in the latter of the industrial revolution. Again, any help is appreciated.

I am writing an essay on the use of horses and their comparative effectiveness in the Great Sioux War. My difficulty has been in finding sources for this topic: something that I would regard as perhaps too general and too "obvious" to be recorded historically (in my mind, no historian would write about the effectiveness of horses in a war that concerns Great Plains Native Americans, for it is likely a given or piece of common knowledge). I’ve looked at few resources so far, one being Lakota and Cheyenne: Indian Views of the Great Sioux War, 1876-1877 by Greene, Jerome A., but it really only was an anthology of Native American views of the war. Some other elaborations of the question that can come off the top of my head are:

1. The 1870's is a time of industrialization in America; did the emerging technologies of the times diminish the value of a horse in the Great Sioux War?
2. How valuable were horses compared to other means of transportation/ communications/ battle forces in the Great Sioux War? It would be great to consider both sides of the war; Americans and native Americans. Even if it is just to say that my assumption of "this is too obvious" is wrong, any help from a list of books to check to a connection to a tribe member or professor that could help would be great.