Google hasn't helped much of course. All I've read along these lines is The Sorrow of War, which was excellent although a little lib. I recently found a memoir of a guy who fought in the Tamil Tigers, but I thought the book needed a little editing. I am, of course, not interested in fascist memoirs (of Japanese soldiers, for instance).
"A Long Way Gone: Memoirs of a Boy Soldier" by Ishmael Beah. Beah was a child soldier during the Sierra Leone Civil War on the side loyal to the government. When this was published, it was one of the few sources on child soldiers written by a child soldier.
"The Fixer" by Joe Sacco. Comic book written by gonzo journalist Joe Sacco. It recounts the story of Neven, who was Sacco's guide during the Bosnian War. Nevin had become a fixer later in the war, selling his services to journalists from a hotel lobby. Neven had previously been a sniper in the Yugoslavian army before joining a paramilitary unit when Sarajevo went under siege. He was briefly involved with the Italian mafia around Naples. How much of Neven's life is true remains a mystery (Sacco even had doubts), but it's a fascinating look at a being a mercenary during one of the worst humanitarian crises post-WWII.