Edouard-Marie Vaillant was born in Vierzon, France, on 28th January, 1840. Originally educated as an engineer he later studied medicine in Paris, Heidelburg and Vienna.
On his return to France he advocated socialism and in 1871 participated in the Paris insurrection in March, 1871. After the defeat of the Paris Commune Vaillant fled to London where he met Karl Marx. In his absence Vaillant was sentenced to death.
Vaillant returned to France in 1880 after the death sentence had been withdrawn. He continued to be active in politics and served as a municipal councillor. In 1893 he was elected to the National Assembly.
In 1900 a group of socialists led by Vaillant and Jules Guesde formed the revolutionary Socialist Party of France. The party failed to make much progress and in 1905 it merged with the French Socialist Party under the leadership of Jean Jaurés.
Although a lifelong pacifist Vaillant supported France's involvement in the First World War. Edouard-Marie Vaillant died in Paris on 8th December, 1915.