BOOK REVIEW / NONFICTION : U.S. Leaders of the 20th Century : IN THE TIME OF THE AMERICANS: FDR, Truman, Eisenhower, Marshall, MacArthur--The Generation That Changed America’s Role in the World <i> by David Fromkin</i> ; Knopf $30, 618 pages

“Dead white males” may be an object of disdain in certain academic circles, but in this new book, David Fromkin argues that a certain generation of American political and military leaders still matters.

FDR and the other key figures in Fromkin’s book--Harry Truman, Dwight Eisenhower, Douglas MacArthur and George Marshall--were all born in the 19th Century and yet they fundamentally redefined the role that the United States was to play in world affairs in the 20th Century.

“Born in a candlelit, horse-drawn world,” Fromkin sums up, “they were to be called upon one day to design the nuclear age.”

Fromkin, a Boston University professor, is the author of “A Peace to End All Peace: Creating the Modern Middle East,” (H. Holt & Co., 1989) a superb account of the makings of the modern Middle East, and he brings many of the same qualities that distinguished his earlier book to “In the Time of the Americans,” including a gift for explaining complex ideas and events in accessible prose, and a palpable passion for his subject.

Fromkin has written the biography of an entire generation by focusing on FDR and his fellow leaders, and he explores who these men were, how they were raised, what they were taught to believe about America and its place in the world. The “dialogue” between Teddy Roosevelt and Woodrow Wilson, he explains, inspired in FDR’s generation a vision of America as the prime mover in world affairs and world history.

“Their belief that their privileged birth as Americans brought with it responsibilities,” Fromkin writes, “carried over at some point into the belief that America’s newly earned great wealth and growing power required the United States to provide not merely a moral example, but also moral leadership, for the rest of the world.”

Moral leadership, of course, is often a euphemism for what we might recognize as politics, diplomacy and war, and these are the real concerns of Fromkin’s book. His book is often less a work of biography than a work of history, and the principal figures--FDR, Truman, Eisenhower and the rest--are overshadowed by the sheer scope and sweep of his historical narrative.

Now and then, however, Fromkin pauses to focus on some incident in the lives of these famous men that prefigures and explains the larger roles that they would play in world history.

MacArthur, for example, is shown as a young Army captain on the loose in Mexico, carrying out a “one-man reconnaissance patrol” and surviving a series of “fast-action gunfights” with the derring-do of a Dirty Harry. His superior officer recommended a Medal ofHonor--but a board of inquiry quashed the decoration precisely because the mission itself had been conducted outside of the chain of command.

We see Truman, too, as a young officer in command of an artillery battery in World War I. “Tonight I’m where I want to be,” he declared to his troops in a battlefield speech at the opening of the Meuse-Argonne offensive. “I’d rather be right here than be President of the United States. You boys are my kind. Now let’s go in!”

More often, though, Fromkin tends toward more abstracted accounts of wars and revolutions, crashes and recessions, treaty negotiations and economic conferences. And he invokes some less commanding figures--William Bullitt, for example, and Walter Lippmann--almost as often as the men named in the subtitle of his book.

Perhaps that’s why Fromkin’s new book somehow lacks the cutting edge of his masterwork, “A Peace to End All Peace.” When he wrote about diplomacy in the Middle East in the aftermath of World War I, Fromkin was touching upon a controversy that is even hotter today than it was 75 years ago.

“In the Time of the Americans,” by contrast, is no less accomplished in its scholarship or its sweep, but it is more difficult to recognize the answers to the crises of our own era in the worldview of FDR’s generation.

Somehow, as I read Fromkin’s book, I began to wonder whether we ought to be more concerned with the life and destiny of some still-nameless man or woman in Bosnia or Iraq or the West Bank whose worldview may turn out to be far more decisive in the century that is upon us.