Seldom has such masterly history been written so well and so soon after the events it recounts. At his death early in 1946, Harry Hopkins left a vast amount of documentary material -- letters, memoranda, copies of state papers and the like. Mr. Sherwood, a playwright who himself was a member of the White House circle, in preparing this best of all the war books, exploited not only this treasure but additional material which was put at his disposal by other actors in the drama, here and abroad. The figure of Roosevelt comes more and more to dominate the book as it progresses through the years of neutrality, until in the war the onetime social worker becomes almost the President's other self. Sherwood tells the story as the record reveals it, without hero-worship. Despite its length of nearly one thousand pages, the narrative moves along with verve and is studded with the texts of immensely important documents.