How many Americans, one wonders, if stopped and asked point-blank, could tell the number of Defense Secretaries this nation has had so far, or when the post was first filled? Very few, probably, and almost none could name them all. But there have only been eight of them, and the office itself is not yet out of its teens. At least four of the eight, each for quite different reasons, have been the kind of men who will not be forgotten by the makers of historical myths: James Forrestal, George Marshall, Charles (""Bird-dog"") Wilson, and of course Robert Strange McNamara. The Pentagon, that ""concrete cobweb"" from which a vast and powerful operation is run, each year requires ""a donation equal to nearly $275 from every man, woman and child in the country."" Mr. Borklund gives a great many facts about its day to day functioning, and all the delicate arrangements of civilian and military machinery necessary to make it work. One might have wished for a more critical accounting of some careers or greater detachment in respect to the department's larger judgments, but given the subject and the paucity of impartial sources, he has succeeded reasonably well.