Alfred Dreyfus is significant in world history because his case showed the depth and strength of anti-Semitism in Europe (specifically in France) around the turn of the century. In addition, his case showed the importance of the splits between conservatives and liberals in Europe at the time.
Dreyfus was a French military officer who was a Jew. In 1894, he was found guilty of having been a spy for Germany. The evidence against him later turned out to be forged and was, in the first place, very sketchy. After he was imprisoned, the Germans continued to get intelligence from France, implying that Dreyfus was not the guilty party.
The debate over Dreyfus’s guilt or innocence split France. On the one side, there were anti-Semites as well as other conservatives and the French Army, which did not want to be seen to have convicted the wrong man. Against them were the liberals and socialists who felt that the case showed the ways in which the conservative establishment abused people’s rights.
A second court martial convicted Dreyfus again, even after the officer who had forged the evidence committed suicide. Dreyfus was eventually pardoned. The Dreyfus case split France on political lines and it also showed how strong a force anti-Semitism was.