What was the Dreyfus affair?

On October 15, 1894, Captain Alfred Dreyfus was arrested and accused of espionage in France. From the article:

"What was the Dreyfus affair?
A scandal that rocked France in the late 19th and early 20th centuries, the Dreyfus affair involved a Jewish artillery captain in the French army, Alfred Dreyfus (1859-1935), who was falsely convicted of passing military secrets to the Germans. In 1894, after a French spy at the German Embassy in Paris discovered a ripped-up letter in a waste basket with handwriting said to resemble that of Dreyfus, he was court-martialed, found guilty of treason and sentenced to life behind bars on Devil’s Island off of French Guiana. In a public ceremony in Paris following his conviction, Dreyfus had the insignia torn from his uniform and his sword broken and was paraded before a crowd that shouted, “Death to Judas, death to the Jew.”

In 1896, the new head of the army’s intelligence unit, Georges Picquart, uncovered evidence pointing to another French military officer, Major Ferdinand Walsin Esterhazy, as the real traitor. However, when Picquart told his bosses what he’d discovered he was discouraged from continuing his investigation, transferred to North Africa and later imprisoned. Nevertheless, word about Esterhazy’s possible guilt began to circulate. In 1898, he was court-martialed but quickly found not guilty; he later fled the country. After Esterhazy’s acquittal, a French newspaper published an open letter titled “J’Accuse…!” by well-known author Emile Zola in which he defended Dreyfus and accused the military of a major cover-up in the case. As a result, Zola was convicted of libel, although he escaped to England and later managed to return to France.

The Dreyfus affair deeply divided France, not just over the fate of the man at its center but also over a range of issues, including politics, religion and national identity. In 1899, Dreyfus was court-martialed for a second time and found guilty. Although he was pardoned days later by the French president, it wasn’t until 1906 that Dreyfus officially was exonerated and reinstated in the army."