Here’s an excerpt from The Origins of Totalitarianism, Chapter 4, “The Dreyfus Affair”:
While the Dreyfus Affair in its broader political aspects belongs to the twentieth century, the Dreyfus case, the various trials of the Jewish Captain Alfred Dreyfus, are quite typical of the nineteenth century, when men followed legal proceedings so keenly because each instance afforded a test of the century's greatest achievement, the complete impartiality of the law. It is characteristic of the period that a miscarriage of justice could arouse such political passions and inspire such an endless succession of trials and retrials, not to speak of duels and fisticuffs. The doctrine of equality before the law was still so firmly implanted in the conscience of the civilized world that a single miscarriage of justice could provoke public indignation from Moscow to New York. Nor was anyone, except in France itself, so "modern" as to associate the matter with political issues.6 The wrong done to a single Jewish officer in France was able to draw from the rest of the world a more vehement and united reaction than all the persecutions of German Jews a generation later. Even Czarist Russia could accuse France of barbarism while in Germany members of the Kaiser's entourage would openly express an indignation matched only by the radical press of the 1930’s.
The dramatis personae of tile case might have stepped out of the pages of Balzac: on the one hand, the class-conscious generals frantically covering up for the members of their own clique and, on the other, their antagonist, Picquart, with his calm, clear-eyed and slightly ironical honesty. Beside them stand the nondescript crowd of the men in Parliament, each terrified of what his neighbor might know; the President of the Republic, notorious patron of the Paris brothels, and the examining magistrates, living solely for the sake of social contacts. Then there is Dreyfus himself, actually a parvenu, continually boasting to his colleagues of his family fortune which he spent on women; his brothers, pathetically offering their entire fortune, and then reducing the offer to 150,000 francs, for the release of their kinsman, never quite sure whether they wished to make a sacrifice or simply to suborn the General Staff; and the lawyer Démange, really convinced of his client's innocence but basing the defense on an issue of doubt so as to save himself from attacks and injury to his personal interests. Lastly, there is the adventurer Esterhazy, he of the ancient escutcheon, so utterly bored by this bourgeois world as to seek relief equally in heroism and knavery.According to Arendt, the Dreyfus Affair received such great attention from the politicians, intellectuals, and the public, and continues to be relevant after two World Wars, because of two elements which grew in importance during the twentieth century: “The first is hatred of the Jews; the second, suspicion of the republic itself, of Parliament, and the state machine.”
Arendt connects the Dreyfus Affair with the Panama Scandal, which broke out a few years before Alfred Dreyfus was accused and convicted of espionage for Germany. The Panama Scandal exposed several French politicians and civil servants who were using Jewish middlemen to accept bribes for keeping quiet about the financial woes of a shady company engaged in building a canal in Panama. The involvement of the Jews contributed to the rise of French antisemitism.