An Informal History of the Civil War"" -- such is the sub- title. And, to this reader at least, it proves to be journalism par excellence and grand reading. His previous book, The Heroic Years, established him as a popular historian. This substantiates that reputation. He has the faculty for making history read like fiction, for infusing it with the human element, so that it seems timeless. The battles are as vividly handled as though he had been correspondent on the scene.