Beyond Baghdad: Postmodern War and Peace, by Ralph Peters, Stackpole Books, $22.95 RALPH Peters is the retired U.S. Army lieutenant colonel known to regular readers of the Post's opinion pages as a tough, patriotic columnist, the one who predicted the course and outcome of our most recent wars with astonishing accuracy. But those readers know only a portion of the man, and "Beyond Baghdad," a collection of Peters' writings over the last couple of years, will allow them to see more. The rest is certainly worth seeing, because Peters is one of the most remarkable American strategists of our time....