On the outbreak of the Franco-Prussian War, he was editing Les Droits de l'Homme at Montpellier, and had to take refuge in Geneva in 1871 from a prosecution instituted on account of articles which had appeared in his paper in defence of the Paris Commune.

In 1876, he returned to France to become one of the chief French advocates of Marxism, being imprisoned for six months in 1878 for taking part in the first Parisian International Congress.

[4] Guesde, who was in prison at the time, was the author of a resolution moved by the delegates from Paris at the Socialist Workers' Congress (1879) and carried by a large majority.

Seeing that the present system of property is opposed to those equal rights that will condition the society of the future; that it is unjust and inhuman that some should produce everything and others nothing, and that it is precisely the latter who have all the wealth, all the enjoyment, and all the privilege; seeing that this state of affairs will not be put an end to by the good-will of those whose whole interest lies in its continuance; the Congress adopts as its end and aim the collective ownership of the soil, the subsoil, the instruments of labour, raw materials, and would render them for ever inalienable from that society to which they ought to return.

He brought forward various proposals in social legislation forming the programme of the Workers' Party, without reference to the divisions among the Socialists, and, on 20 November 1894, succeeded in raising a two days' discussion of the collectivist principle in the Chamber.

[8] His defence of the principle of freedom of association led him, incongruously enough, to support the religious Congregations against Émile Combes's Separation of the Churches and the State.

During the revolt of the Languedoc winegrowers on 11 June 1907, Jaurès, who defended the vine growers cause in the Chamber of Deputies, filed a counter-bill with Jules Guesde.