“Henry Adams and the Making of America” (Houghton Mifflin, 468 pages, $30) is not just a book; it is an act of piety, or perhaps of chivalry, performed by one of today’s most popular historians towards one of his most unjustly neglected predecessors. Of course, Henry Adams can hardly be called a forgotten figure in American literature. His grandly pessimistic memoir, “The Education of Henry Adams,” is an undisputed classic, and his novel “Democracy” is still considered one of the best fictional treatments of Washington politics. But the very success of the “Education” – an autumnal work, written in 1907, when Adams was 69 years old – has overshadowed the achievement for which he was best known in his own time: his massive history of the early American republic.

The nine volumes of Adams’s “History of the United States of America During the Administrations of Thomas Jefferson and James Madison” constitute one of the major achievements of a golden age of narrative history writing. In the 19th century, historians like Carlyle and Macaulay in England, and Prescott and Motley in America, combined a Gibbonian sense of scope and style with a new understanding of how to use archives and source materials. In their multi-volume works on the crucial events of the modern period – the French Revolution, the English Revolution, the Dutch war of independence, the conquest of America – these great Anglo-American historians not only shed new light on the past. They elevated history writing to an important branch of English literature, worthy of comparison to the best histories of the ancient world, or the best novels of their own time. That these historians are comparatively little read today has something to do with changing standards of historical scholarship, but more with simple literary amnesia.

For Garry Wills, the chief victim of that amnesia is Adams’s “History,” which he considers “the non-fiction prose masterpiece of the nineteenth century in America.” While Adams’s work has hardly disappeared – it is in print in the Library of America, and remains an important source for students of the early republic – it is undeniable that, as Mr. Wills complains, the “History” is “little read, appreciated, or studied.”

“Henry Adams and the Making of America” is devoted to changing this state of affairs. In its first, shorter section, “The Making of a Historian,” Mr. Wills sketches Adams’s career as a scholar, arguing that his accomplishments have been obscured by the laziness of his critics, and by the long shadow of his own “Education.” In the longer second section, “The Making of a Nation,” Mr. Wills offers a digest of the “History,” summarizing its nine volumes in 13 chapters of his own. This digest is necessarily dry, and omits much of the context that the general reader needs to make sense of the complex political and diplomatic affairs that Adams discusses. But it gives a sense of the scope of Adams’s “History,” and offers a compact introduction to American political and diplomatic history of the period 1801-15.

In writing about the Jefferson and Madison administrations, Adams was quite conscious of the burden of his own name. Adams’s great-grandfather was John Adams, the last Federalist president, whom the Virginian Jefferson defeated in the election of 1800; his grandfather was John Quincy Adams, whose single term in office was the last gasp of New England dominance before the West came to power in the person of Andrew Jackson. To be an Adams in the late 19th century was to be yesterday’s man, a republican aristocrat in an age of mass democracy. Or so Henry Adams himself led posterity to believe, thanks to the famously embittered self-portrait of the “Education”: “What could become of such a child of the seventeenth and eighteenth centuries, when he should wake up to find himself required to play the game of the twentieth?”

Reading backward from the famous “Education,” Mr. Wills shows, historians have expected to find in the “History” nothing but hostility to Jefferson and Jeffersonian democracy. As a result, some of Adams’s critics have not even bothered to read beyond the first chapters, with their portrait of a provincial and stagnant America: “Who, after all,” Mr. Wills writes, “wants to suffer through nine volumes … of a pessimistic attack on democracy and the nation?” But as Mr. Wills goes on to show, Adams opens his work with a dim view of the young republic precisely in order to show how it matured under the stewardship of Jefferson and Madison. His account of their administrations, far from being warped by Adamsite grievance, argues that the Republicans accomplished what the New England Federalists never could: They transformed a small postcolonial country into a vibrant continental power. The Adams of the “History” is not the disappointed mandarin of the “Education,” Mr. Wills insists, but “a man optimistic, progressive, and nationalistic.”

In the first half of his book, Mr. Wills shows how Adams’s early career equipped him to write a history so different from what family and regional bias might have predicted. Adams was conscious of his family’s traditions, even cripplingly so, but he was far from complacent about them. He made a point of identifying with the one Southerner in his family tree, his grandmother Louisa Johnson, whose private papers were full of bitter grievances against her husband, John Quincy, and her mother-law, Abigail.

As a young man, Henry Adams saw history in action as private secretary to his diplomat father, Charles Francis. His observations of Washington in the secession winter of 1860 taught him more than any textbook about the realities of power in Cabinet and Congress. And his experience teaching medieval history at Harvard, and editing the influential North American Review, put Adams in touch with the newest developments in historiography.

All of this training paid off when, in the 1880s, Adams turned to writing the “History.” His chosen period is not the most inspiring in American history. Indeed, from 1801 until the War of 1812, U.S. government policy was a long and mostly unsuccessful improvisation. If Adams compared Jefferson to a figure in a Beaumarchais comedy, it was only because, surprisingly, all of his blunders turned out for the best in the end: The United States acquired Louisiana from the French, defeated the British at New Orleans, and set out on its course of continental mastery.

Mr. Wills’s account of the period’s diplomatic twists and turns is not for the faint of heart, and assumes a fair amount of background knowledge. Indeed, Mr. Wills might have been happier breaking “Henry Adams and the Making of America” into two books: a biography of Adams, which could have delved into his intellectual life more deeply, and a history of the early republic, which could have gone into the subject more thoroughly. Even in its present, double-humped form, however, Mr. Wills’s book succeeds in its stated goal: It makes the reader eager to experience Adams’s “History” first-hand.