I am trying to figure out what the name of a book is, which I read 15 years ago as a kid.
It is about a guy who travelled through some sort of portal (I do not know because this happened in a earlier book from this series, I believe) in the Vietnam jungle and got stuck in a new world. On this world he fights in an army for princes, dukes etc. The cover was dark red and paperback. Although I can vaguely remember him sitting on some kind of animal on the cover, I am not 100% certain. Could someone please help me find this book?
Thanks in advance.