Two centuries of German history are brought into focus through the lens of a strategically placed, highly interesting family. American journalist Friedrich's (Olympia: Paris in the Age of Manet, 1992, etc.) 14th book takes up the aristocratic von Moltke clan. The family first came to international prominence with General Field Marshal Helmuth Count von Moltke, the great military strategist and architect of Prussian victories over the Austrians (1866) and the French (187071). Friedrich tarries perhaps too long over the tactical details of famous battles and not long enough on the mind of this remarkable man. And occasionally the more vivid personality of Otto von Bismarck runs away with the show. Bismarck gets all the good lines, as when he likens the way he manages the Prussian sovereign to handling a balky horse who ``takes fright at an unaccustomed object, will grow obstinate if driven, but will gradually get used to it.'' Von Moltke was by contrast a man of few words. Though other von Moltkes crop up here and there, the book's remaining third is mainly concerned with the field marshal's heroic descendant, Helmuth James von Moltke. A man of clear mind, independent conscience, and firm resolve, this von Moltke opposed Hitler and the Nazis and hoped to help steer Germany back on the track of decency. He was at the center of a resistance group that plotted the assassination of Hitler, though von Moltke himself was opposed to the killing. In 1944 the Gestapo arrested him, and after being found guilty of treason, he was executed in 1945. He is survived by his wife, Freya von Moltke, who was a principal source for Friedrich's account. Friedrich's emphasis on only two members of the family, together with the rather more vivid presence of Bismarck, gives the book a sense of unbalance. Though often engaging, it does not finally cohere as the story of a whole family. (maps and photos, not seen).