Even if you're not a Star Wars fan, the Republic Commando series (paperback, five titles) is a good read.
War, citizenship, slavery, love, hate, brotherhood, PTSD, family (both the kind you're issued and the kind you acquire)....all in there.
Unlike most SW books, the Jedi have a fairly small role. I describe them as a military series which just happened to be in the SW universe. The author, Karen Traviss, was a Brit in their reserves and spoke to a lot of currently serving guys (including me). I ended up emailing her a thank you and we corresponded for a while. The series has helped a couple of bros who had issues coming back from the war.
Dungeon, Fire and Sword: a good look at the Templar order and just how screwed up the Crusades were in general.
Anything fiction by David Weber and/or John Ringo is generally good, the Honor Harrington series has an entire shelf in my library.
Anything you can find still in print by Teddy Roosevelt is good shit.