The events that took place in Haiti, then a prosperous French colony known as St. Domingue, between 1791, when the great slave rising began, and December 1803, when the country’s independence was proclaimed, probably changed U.S. history. Napoleon’s defeat in Haiti meant that he could no longer secure Louisiana, which he wanted to use as a base for his imperial designs in North America, so he ended up selling it to the U.S. That sale—the Louisiana Purchase—opened a big national debate in America about whether the states to be created in the newly acquired territory would be slave states or free states. Haiti’s successful slave revolution lit up the imagination of both abolitionists and slave owners in the U.S., contributing to the turmoil that, in the decades that followed, led to the Civil War.

It is surprising, given these umbilical connections, that Americans have paid a lot less attention to Haiti than to other parts of the Western Hemisphere. Madison Smartt Bell, a novelist who wrote a fictional trilogy based on Haiti’s independence struggle a few years ago, is an exception. He now returns to Haiti with a well-researched and elegantly written biography of the hero of that struggle: Toussaint Louverture.

His subject did not initiate the slave rebellion, nor was he the man who 12 years later proclaimed the country’s independence. But, unlike the names of the leaders who sparked off the rising, Louverture’s did not fade away into oblivion; and unlike Jean Jacques Dessalines, the man who went on to declare Haiti’s independence, he was much more than a megalomaniacal, blood-thirsty tyrant. He was a complex and contradictory character in whom it is possible to identify as many edifying traits as unpleasant ones and in whose biographical tale there are enough lacunae to warrant the intuition of the novelist rather than the erudition of the historian.

Louverture was the grandson of a tribal leader from Africa’s Dahomey Coast and the son of a slave who had been sold to the count of Bréda in St. Domingue. The Bréda plantation was one of the many estates that produced Haiti’s abundant sugar exports, making Haiti the most valued colony in the Western Hemisphere. The island, colonized by Spain in the 16th century, had gradually come under French control by the 17th century as Spain’s attention shifted to Peru and Mexico, which had vast reserves of gold.

Haiti’s colonizers responded to the decline of the native population by importing slaves from Africa. By the end of the 18th century, those slaves numbered nearly a half-million, comprising by far the largest segment of the population. Although there had been previous episodes of rebellion, the French Revolution and its claims to the “rights of man” triggered the first organized attempt against the prevailing system. By the time Louverture was approaching the age of 50, a free citizen and even a property owner (he had been manumitted by the count of Bréda in 1777), the island was in a state of agitation.

A Natural Leader

The rebellion was a bloody one, eventually claiming hundreds of thousands of lives and leading to a succession of brutal regimes. In 1791, slaves in the north of the country—inspired by a religious leader named Boukman—rose up against their masters, slaughtering thousands. The fighting evolved into a civil war that would continue until the defeat of Napoleon’s troops 12 years later.

Louverture’s role was pivotal. He was a natural leader and military strategist who managed to unite under his command many blacks, whites and mulattoes. The former slave confronted the Republicans at first, allying himself with the royalists, including the Spanish monarchy: It controlled the western half of the island (the present-day Dominican Republic) and had its eyes set on French St. Domingue. After France abolished slavery, Louverture switched sides, helping crush the Spaniards and eventually brokering a deal with the British, who had also invaded Haiti, thus liberating his country from foreign intervention.

But Louverture’s attempts to enforce a constitution that granted him power for life and in effect severed Haiti from France led Napoleon to send an army against him. The French captured Louverture and sent him to a prison near the Swiss border, but the toll of the war was so heavy on the French that Napoleon would eventually come to regret having ordered the invasion. The island then fell under the control of Dessalines, who destroyed the remaining French forces. Louverture died in prison a few months before the declaration of Haiti’s independence.

Mr. Bell’s portrait of Louverture is as honest as his overall assessment of his actions is generous. Louverture was indeed full of contradictions. He was a former slave who had owned slaves himself before the black rising. He imposed forced labor on his countrymen after 1800, when he managed to gain control of a country that until then had been—over the centuries—a theater of war between royalists and Republicans, between whites, mulattoes and blacks, and between France, Spain and England. He made a life cause of the fight against tyranny and yet proclaimed himself governor for life in 1801. He expressed disgust with the exactions of his rivals, notably the mulatto leader Antoine Rigaud, and yet he ordered a massacre of Spaniards in 1794, when he put an abrupt end to his alliance with the Iberian monarchy and embraced the French Republicans. He also tolerated the extermination of 10,000 mulattoes at the hands of Dessalines, then one of his lieutenants, in 1800.

Mr. Bell does not conceal any of these episodes, but his favorable inclination toward Louverture leads him to relativize his conduct: “For a citizen of what we are pleased to call the First World, the apparent contradictions of Toussaint’s personality can be difficult to resolve. Within Haitian culture, there are no such contradictions, but simply the actions of different spirits which may possess one’s being under different circumstances and in response to vastly different needs. There is no doubt that from time to time Toussaint Louverture made room in himself for angry, vengeful spirits, as well as the more beneficent lwa.” The irony of this observation is that, although Toussaint sporadically used Vodou for political purposes—Voudou was the religion of most of Haiti’s inhabitants and continues to be practiced by half the population today—he was a self-proclaimed Catholic and a very “Westernized” Haitian.

In passing judgment on Toussaint, one should take into account his legacy—the political actors and the institutions that he helped bring about and that survived him. And here is where Mr. Bell is perhaps too lenient. After defeating the remnants of the French army, Toussaint’s successor, the delirious Dessalines, went on to crown himself emperor and to establish a genocidal tyranny, only to be followed by new dictators. In effect, France’s oppressive colonial rule was replaced with homegrown despotism. Toussaint’s cause had been liberation and yet—despite his relative moderation, his efforts to welcome back white plantation owners and his intelligent dealings with the U.S. and Britain—he failed to establish the foundations of a more participatory and just society.

What had started as something more ambitious than the American Revolution—which, as Mr. Bell reminds us, had not intended to overturn an entire socioeconomic system in the way Haiti’s slaves set out to do—ended up creating a dysfunctional state. Part of that tragedy stems from the fact that Haiti’s most enlightened leaders—like Toussaint but with fewer redeeming qualities—continuously betrayed the hopes of ordinary people up to this day. One of them is Jean-Francois Aristide, who in recent times probably had the best shot at founding a new republic but opted instead for behaving like a thug. The coup that deposed in 2004 has brought only a slight amelioration to Haiti’s fortunes. The island continues to suffer a lack of social and political stability.

The work that best captures Haiti’s abundant charms and maddening history is Alejo Carpentier’s famous 1949 novel, “Haiti, The Kingdom of This World,” which describes the surreal atmosphere of the revolution with poetic prose. Upon finishing Mr. Bell’s compelling biography of Toussaint Louverture, one can do no better than to pick up Carpentier—to understand even better just why dictatorship has been a recurring fact of Haiti’s modern history.