Some readers of this blog mentioned to me military-related literature that they read.
I have two Defence & Freedom links for you that might help a bit with your personal journey through such literature.
One is my list of book recommendations:
The other is about my experience with old literature, with (what I consider) insights about what kind of reading makes sense and what's quite a waste of time:
Also, keep in mind there's an interlibrary loan service in many developed nations. You can usually get these books for a few weeks at almost no cost. I ordered a book worth 110 € in Amazon recently. Soon I'll be able to read it for six weeks (there are copies in German public libraries, I checked that) and it costs me only 2.50 €.
edit: Damn, I forgot the GIF. I had it stored for months, waiting for an opportunity to build it into the blog!