"At the end of September, in 1919, the presidential train bearing Woodrow Wilson on a Western tour of speechmaking in his last-ditch, desperate effort to rally the nation behind the ratification of the Versailles Treaty of Peace, which the Senate seemed determined to nullify, pulled into Wichita, Kan., where a large crowd had gathered at the station to hear him," Louis Auchincloss begins. "After a 15-minute wait the president's secretary, Joe Tumulty, appeared and announced gravely that his chief was suffering from 'nervous exhaustion' and could not make the address. The train then headed directly to Washington." The minor stroke aboard the train was followed by a major stroke on Oct. 2, which at once paralyzed the president and the government. From that point onward, the political and personal tragedies of Woodrow Wilson were one. While the treaty went down to defeat in the Senate, dooming his hopes for the League of Nations, Wilson cut himself off from one friend after another, including his closest aide, Col. Edward M. House. (Whether the failure of the United States to join the League of Nations was a tragedy may be debated; as League members, Britain and France failed to stop German, Italian and Japanese aggression, and it is doubtful that the United States, which had to be bombed into World War II, would have been driven to act earlier by a mere collective-security treaty.)

The story of Thomas Woodrow Wilson is material for a tragedian, an American Shakespeare. Auchincloss, an American novelist and man of letters, is the next best thing. The esprit de finesse, the mastery of motive, that informs Auchincloss's more than 50 books of fiction and nonfiction complements Wilson's esprit de geometrie, his devotion to abstract principle. The match of subject, writer and genre in "Woodrow Wilson" is perfect.

The genre of the brief life forces the biographer to concentrate on the years in which a person of historical importance does the work for which he is remembered (a span that may be only a fraction of a lifetime). Woodrow Wilson divides neatly into two parts: 1856-1914 and 1914-24. With a novelist's interest in the formation of character, Auchincloss describes the early years of Tommy Wilson, who was born in Virginia but grew up in Augusta, Ga., where his father, Joseph Wilson, became the chief executive of the Southern Presbyterian Church. Because Wilson's father came from Ohio and his mother, Jessie Woodrow, from England, Auchincloss writes, "Wilson's claim to be a Southerner had in it something of the factitious. Although it is true that he lived in Virginia and Georgia until he was in his late 20's, he had no Southern ancestry, and he resided in the North for the balance of his life." But surely someone who lives in a single region until he is nearly 30 is a product of that region. "He used to say," Auchincloss notes, "that the South was the only part of the country where nothing had to be explained to him." Indeed, Wilson was the first Southerner to be elected president since the Civil War, and he started a trend: if Harry Truman and Lyndon Johnson are considered Southerners, then five of seven Democratic presidents in the 20th century came from the South.

After an abortive start in the legal profession, Wilson attended graduate school at Johns Hopkins and taught history and political science at Bryn Mawr, Wesleyan and, beginning in 1890, at Princeton, his undergraduate alma mater. While battling snobbery among students and alumni as president of Princeton and publishing an impressive number of articles and books, including the acclaimed "Congressional Government" (1885), Wilson dreamed of influencing public affairs. Auchincloss, who has written about early modern France, observes, "His precedent is more to be found in Europe than in America, more in the example of some young priest like the 17th-century Richelieu dreaming in the cloister of how he might take over the power of the state from the clumsy military minds that had ruled it so long." If Auchincloss knew the South better, he would recognize Wilson as an example of a kind that also includes Thomas Jefferson and John C. Calhoun: the Ciceronian humanist who moves with ease between politics, philosophy, journalism and literature, a type that survived in the provincial South for generations after specialization destroyed its habitats in Britain and the American North.

Wilson owed his chance to be a philosopher-king to Democratic Party philosopher-kingmakers who made him governor of New Jersey in 1910 and then arranged for his nomination as president in 1912, to block another disastrous presidential bid by William Jennings Bryan, the party's three-time nominee. (Resurfacing as Wilson's secretary of state, Bryan, a prohibitionist as well as an agrarian and creationist, replaced wine with lemonade at State Department receptions before resigning in protest over the administration's preparedness policies.) Wilson was elected president in 1912 only because Theodore Roosevelt's Progressive Party candidacy split the Republican vote that otherwise would have re-elected T.R.'s estranged successor, William Howard Taft. Once in office, Wilson surprised conservative Democrats by pushing through a number of progressive reforms in the name of the "New Freedom," the Democratic answer to Roosevelt's "New Nationalism." For most of his presidency, Wilson relied on the political skills of a Texan adviser, Colonel House, whom he described as "my second personality. He is my independent self." It is as if Jim Baker had been the best friend and counselor not of George Bush but of Jimmy Carter.

The constraints of the brief biography prevent Auchincloss from dealing with the complexities of the Wilson administration's foreign policy in the years preceding World War I. Like most historians, he treats Wilson's involvement in Mexican politics as an isolated episode rather than as part of a regional strategy to pre-empt German influence. Wilson sent American troops to occupy Haiti in 1915 and the Dominican Republic in 1916, and a year later the United States bought the Virgin Islands, thereby gaining control of every major Caribbean island except British Jamaica. The Zimmerman telegram, in which Germany promised Mexico the return of Texas and California in return for an anti-American alliance, suggests that the fears of the Wilson administration were not unjustified. (Wilsonian Realpolitik in the Caribbean and Mexico backfired when Wilson's former assistant secretary of the Navy, Franklin D. Roosevelt, ran for vice president in 1920. Joking about his qualifications, F.D.R. said: "You know I have had something to do with the running of a couple of little republics. The facts are that I wrote Haiti's Constitution myself, and, if I do say it, I think it a pretty good Constitution" -- giving the Republican presidential candidate, Warren G. Harding, an occasion to denounce the alleged "rape of Haiti" and other West Indian islands.)

The entry of the United States into the Great War in 1917; the Fourteen Points; the arrival of Wilson in Europe, hailed as a messiah; the clashes between the idealistic American president and cynical European leaders; the battle against membership in the League of Nations led in the Senate by Henry Cabot Lodge (like Wilson, a brilliant professor in politics); Wilson's collapse and repudiation of his friends and allies -- this is a familiar story retold well. Auchincloss argues that the catastrophe was foreshadowed. Wilson suffered a minor stroke as early as 1896, and again in 1906. Auchincloss blames Wilson's second wife, the former Edith Bolling Galt, for his break with Colonel House and others, and adduces evidence that a need for uncritical female devotion was part of Wilson's character all along.

Perhaps, though, poor health and a protective wife were less crucial than his own beliefs in driving Wilson to his downfall. Bismarck famously remarked that the statesman can only listen for God's footsteps and clutch at his robe; another great realist, Charles de Gaulle, when told he was indispensable, replied, "The graveyard is full of indispensable men." President-elect Wilson told the astonished chairman of the Democratic Party after his victory in 1912, "Remember that God ordained that I should be the next president of the United States." His career remains a tragedy but ceases to be a mystery, if one assumes that Woodrow Wilson was sincere in his belief that he was on a mission from God to save the world from war.