Jean Jaurès (1859-1914), the greatest of the modern French Socialists, played a key role in the unification of the Socialist movement and in the struggle to prevent World War I.

On Sept. 3, 1859, Jean Jaurès was born at Castres, Tarn, into a lower-middle-class family. After studies there, he attended the lycée Louis-le-Grand in Paris. His intellect and articulateness won him first place in the 1878 entrance competition for the prestigious École Normale Supérieure, from which he graduated with a philosophy degree in 1881. While teaching at the lycée of Albi and then at the University of Toulouse, he became involved in politics.

In 1885 Jaurès was elected to the Chamber of Deputies from the Tarn as a moderate, unaffiliated republican. In the Chamber he worked for social welfare legislation and spoke vigorously against Gen. Boulanger. Defeated in 1889, he returned...