"-back! Go back, go away, do not go down there, you must help me, go back!"
I gave up on this one after fifty pages; it's a rather routine mil-sf story about a soldier with wonderful technological device working to overthrow the invader, clunky in style, and obvious where it was going from the first few chapters.
Was the unread sf book which had been longest on my shelves. Next on that list is The Host, by Peter Emshwiller.