Longuet was participated in the Paris Commune of 1871. He moved to England as a refugee after the defeat of the Commune. Longuet married Karl Marx's first daughter, Jenny on 2 October 1872 in London in a civil ceremony. Together, they had six children, the first five of whom where boys (including Jean Longuet), the last a daughter. He was one of the speakers at Marx's funeral.
He was also the editor of the publication Journal Officiel.