UNDAUNTED COURAGE Meriwether Lewis, Thomas Jefferson and the Opening of the American West By Stephen E. Ambrose; Simon & Schuster: 496 pp., $30

Stephen E. Ambrose’s “Undaunted Courage” is a story on a big scale with meanings squeezed into a framework built on a considerably smaller scale. There is no question that this is a good and readable story. Meriwether Lewis was an extremely interesting man and writer, and any book with the license to quote him at length carries a competitive advantage.

Repeatedly, Ambrose, a historian best known for his three-volume biography of Richard Nixon and a recent oral history of D-day, locates the meaning of [his] story in lessons of universal military practice. At the Pacific camp, Lewis’ goals in maintaining order and discipline, Ambrose says, were “the goals of every company commander from the time of the Roman Legions to today.” Meanings reaching so far over time can stretch themselves pretty thin. “A good company commander looks after his men,” Ambrose writes, adding that Lewis was like “the head of a family,” evincing concern for his men matching “that of a father for his son.”

Acknowledging that Lewis is one of his heroes, Ambrose argues that the explorer needs to be better appreciated. Lewis’ suicide “hurt his reputation” and deprived him, for instance, of the honor of having a river or another major geographical feature named after him. Those with more of an enthusiasm for wordplay and puns may notice what Ambrose did not: with a minor twist of misspelling, “Louisiana” Territory stands ready for transformation.