The narrator of Anthony Powell’s novel The Kindly Ones mentions that, as young men, he and his friend Moreland “both had taken a passionate interest in the American Civil War and the Dreyfus Case, poring over pictures of those two very dissimilar historical events wherever their scenes and characters could be found illustrated.” The two events, despite sharing space among the half-dozen most interesting things that ever happened, would seem to have little in common. But they are not as dissimilar as they look. Frederick Brown, the great biographer of Zola and Flaubert, argues that the Dreyfus affair was itself a culminating battle in a civil war, albeit of a cultural kind. His new book, For the Soul of France, invites us to view the Dreyfus affair as a conflict generalizable to other polarized political cultures, including ours.

In 1894 a cleaning lady working for French intelligence discovered a letter in the wastebasket of the German military attaché in Paris that indicated a French army officer was passing secret information about new weapons. Suspicion fell on Alfred Dreyfus, an earnest and patriotic Jewish artillery captain. Despite his protestations of innocence and a weak case against him (buttressed by fabrications), he was vilified in the press, stripped of his rank, convicted of treason, and sentenced to a life of solitary imprisonment off the coast of South America. In 1896, with Dreyfus safely jailed, a second letter was taken from the German embassy in which the handwriting exactly matched the first. It belonged to the actual traitor, Ferdinand Walsin Esterhazy, a dissolute and heavily indebted army major. Rather than admit they had arrested the wrong man, high-ranking officers forged evidence and conspired with Esterhazy himself. By the time Dreyfus’s name was cleared in 1906, the main forger had committed suicide, Émile Zola had invented (with his pro-Dreyfus broadside J’accuse!) the role of the modern crusading intellectual, Zola’s lawyer had been shot and wounded in an assassination attempt, France had established the most radical separation of church and state in the West, and a new kind of democratic anti-Semitism had been introduced that three decades later would nearly destroy European civilization.

What made the Dreyfus affair possible was the political polarization of French society. The proximate cause was the rout of the French army in a matter of days after Napoleon III launched a war against Prussia in 1870. French people could not agree on who was to blame for it. Had France been humiliated because it was decadent or because it was backward? Catholics versus republicans is the simplest way to describe the conflict, but you could also say that it pitted tradition against cosmopolitanism, religion against science, repentance against modernization, and those who saw the revolution of 1789 as a new birth of freedom against those who, as Brown puts it, thought it “separated the French from their dead.”

Never granting the legitimacy of the other’s idea of France, each side easily mistook its private interests for national ones. The last decades of the 19th century were a time of morale-sapping financial scandals. The speculator and Catholic philanthropist Eugène Bontoux founded the Union Générale, an investment bank that pitched its services by calling on Catholics to stop investing with “opponents of their faith and their interests” — primarily Protestants, Jews, and atheists. When Bontoux’s profits from Eastern European railroads proved to be a figment of phony bookkeeping, those who would mix God and mammon were discredited, and the progressive, scientific forces gained the upper hand. Their good name did not last long. The builder and promoter Ferdinand de Lesseps, with the engineering help of Gustave Eiffel, launched a bid to dig a canal through Panama. By the time that scheme collapsed, years behind schedule, in 1889, tens of thousands of workers had died, tens of thousands of investors had been bilked out of their life savings, and the Panamanian cordillera had barely been scratched. (The United States would finish the canal in 1914.) De Lesseps’s advisers had bribed French politicians to permit the issuing of bonds, bribed newspapers to not look too closely into the bonds’ soundness, and pocketed tens of millions of francs for themselves. And the two most prominent of those advisers were Jewish.

Already when the Union Générale crashed, one newspaper had blamed the “maneuvers of a group of German Jews.” Now the stage was set for the anti-Semitic outrages of the Dreyfus affair, in which the Jewishness of the accused left much of the public indifferent to the question of his innocence. People began to complain that Jews were overrepresented in all walks of life, even — to take an astonishing instance that Brown cites — on the list of donors to Catholic charities to aid and memorialize the victims of a fire at a charity ball. Édouard Drumont’s La France juive became one of the best-selling books of the 19th century. Zola was particularly discomfited by anti-Semitism. “It stupefied him,” Brown writes, “that such fanaticism should have erupted in an age of universal tolerance ‘when the movement everywhere is toward equality, fraternity, and justice.’” To the extent that Zola saw this as something archaic, he was wrong. The anti-Semitism of which the Dreyfus affair was a foretaste — argued as a political program by sophisticated orators and savvy newspapermen, rather than shouted in villages by angry peasants — has occurred only in the modern age.

What made French society in the late 19th century such a reliable machine for generating intolerance? Despite the slogans of equality, fraternity, and justice, France had — by comparison with England, Germany, or Italy at the time — a stunted conception of liberty. French republicans threw the word “liberty” around a lot, but what they meant was something more normative than neutral. These republicans were not good-government idealists; they were bent on wiping out all competing sources of authority.

Brown lays out these conflicts judiciously and, for the most part, neutrally. He pays considerable (and sympathetic) attention to Jules Ferry, the prime minister and pedagogue who has a claim to be called the father of the French school system. Ferry passed for a “moderate” republican. Yet his solution to the problem of clergy who were “poisoning young minds against the Republic” was to expel the Jesuits from France, and then to disbar the magistrates who raised constitutional objections. When republicans won the national elections of 1878, they de-seated 72 deputies they deemed to have been elected with too much Church support. “What became axiomatic thereafter was the principle that corrupt behavior manifested itself only in conservative ranks,” Brown notes. “No republican legislator would ever face expulsion because a Masonic lodge, an anticlerical schoolmaster, or a like-minded prefect had endorsed his candidacy.”

Brown’s most fascinating chapter concerns the brief rise of Gen. Georges Boulanger, a charismatic but vacillating critic of parliament who appeared to be on the verge of seizing power in a coup in 1889. Boulanger, whose mother was Welsh, spoke fluent English. He had visited the United States and took Andrew Jackson as his model. He proposed revising the French constitution to geld the legislature — an approach no different in principle from what de Gaulle did when he established the present French constitution in 1958. Like de Gaulle, Boulanger was the only politician of his era capable of drawing from both sides of a polarized public. This was partly because Boulanger was slick. He would declare himself a staunch secularist one day and promise to fight to the death for the Church the next. But it was also because he addressed the one conviction both sides truly shared: that the French republic served special interests as efficiently as the ancien régime had, except that the special interests it now served were undeclared.

It is easy to be a Dreyfusard from a century’s distance. We have proofs of Dreyfus’s innocence that his contemporaries lacked, not to mention some wisdom about what unleashing the dogs of anti-Semitism can lead to. But it was a calamity for France when the Dreyfusard “side” cast the exoneration of a man as the vindication of a political platform. The Dreyfus affair should have been a lesson in what happens when elites govern without consensus, but that lesson went unlearned. Brown notes that when, in 1903, the anti-clerical prime minister Émile Combes dedicated a statue to the freethinking philosopher Ernest Renan, in Renan’s native town of Tréguier, he was accompanied by a detachment of police twice the size of the population of the town. Force, and not consent, was the basis of the turn-of-the-century French republic’s legitimacy, and its “Enlightenment values” were supported by troops, not arguments. Two years later, Combes would spearhead passage of the most radical separation-of-church-and-state law in the West. Like the Versailles treaty 14 years later, it breathed new life into a conflict it meant to end, and proved that there is no problem so severe that it cannot be exacerbated by someone trying to solve it once and for all.