Donald Graham on President James K. Polk

To their shock, many American-history readers who loved biographies of Adams, Lincoln, or Jackson will find among their 2009 holiday gifts a biography of—there's no disguising it—James K. Polk. If this happens to you, do not panic. Robert Merry has done the impossible: he has made Polk's presidency fascinating. Merry's portrait of Polk, A Country of Vast Designs, brings this odd man to life: priggish, guarded, courageous in his policies, crafty in his politics, cowardly face-to-face. Merry calls him a "smaller-than-life figure," but Polk is much more impressive than his reputation.

Polk is easily our least-known consequential president. He fought the Mexican War; expanded the Union by settling claims to Texas and the Oregon Territory and by acquiring California and the Southwest; and solidified national economic policy. And—Merry is wholly persuasive in this—he accomplished most of his goals as a result of his own initiative. He was a most astute political leader.

But what an unlikely one! What other president was elected immediately after two defeats (for governor of Tennessee) turned his promising career moribund? Polk spent years maneuvering for the Democratic vice presidential nomination. But when the favored candidate, Martin Van Buren, chose the wrong side on Texas annexation in 1844, Polk's shrewd political team (led by the 19th century's great historian George Bancroft) brought him forward to a deadlocked convention. He was the first dark-horse nominee elected president.

These were early Victorian times, and the Washington of 1845–49 springs to life in Merry's pages as in a good Victorian novel. What a cast: John C. Calhoun, still a ferocious figure two decades after he sparred with Polk's mentor Andrew Jackson; Thomas Hart Benton, an unmanageable mound of ego; Henry Clay, aging, defeated by Polk, but still ingratiating. There's even a previously little-known heroine: Polk's wise and funny wife, Sarah.

And what a villain! James Buchanan, disloyal, unprincipled, and weaselly, displays all the qualities as secretary of state that would make him perhaps American's worst president 10 years later. Polk can't bear him, but the president shows why he was misnamed Young Hickory: in four years he can't bring himself to fire Buchanan. What would Andy Jackson have done to him?

One comes to feel one lives in Polk's time, and perhaps this accounts for the book's sole startling flaw. When Polk left office, as Merry writes, we were on the road to the Civil War. And Merry writes ably about the slavery debates of Polk's last years. But what of Polk himself and slavery? He tried to follow Jackson in pushing slavery to the periphery of national politics by concentrating on other issues (Merry convincingly turns aside the idea that Polk instigated the Mexican War to expand the slave states). But what did Polk think of the institution of slavery? We do not learn. How many slaves did he own? Who were they? Was he a kind or cruel man? When he takes a 10-day vacation in the last year of his presidency, he travels with "a free man of colour" named William Day who had "served as Polk's faithful servant throughout his presidency." It is the first and last we hear of him. Did William Day somehow come from Tennessee—a free man—with Polk? What happened to him after Polk left the White House? Polk saw him regularly, but we never see him again.