One of my favorite resources for genealogical research is old county history books. I have been amazed at the amount of personal family history I have discovered in books written in the early 1900's about Ohio and Illinois. My ancestors were early settlers in both states and to my delight I have found entire biographical paragraphs written about my relatives. The Internet Archive Digital Library is a valuable site for anyone who is looking for these types of history books and the fact that there is no charge for it's use makes it even better! I have had to rely a great deal on the resources that are available to me online, so I am always thankful to discover new websites like this one.
Another site you might wish to check out if you are interested in Army records is The U.S. Army Heritage and Education Center. You can search for Army information, watch videos and more.
Let me know if you make any new discoveries!