As every history buff has known for at least a couple of seasons, World War I is now competing with the Civil War for scholarly and popular attention. If more than a handful of permanent contributions survive, this should be one of them. Mr. Horne has limited his study to ""the grimmest battle in all that grim war"" and has examined every action with the greatest care. This is a fascinating and splendidly articulated microcosm which can better old the general reader's comprehension of the macrocosm- the entire war and indeed many aspects of the half century which has followed it. In ten months, on a terrain less than four miles square, over a quarter of a million men were killed and nearly half a million gassed or wounded. It is all here: the blunders and stupidity, the squandered heroism, the indescribable fear, the hopeless misery, the enormous tragedy. Mrs. Horne has made it both comprehensible and unforgettable.