The artificial language Esperanto, invented by he Polish Dr. L. Zamenhof in the 1880s, was meant as a tool for universal understanding - and world peace. It was quite popular in the workers' movement too. This poster was published by the French branch of the Sennacieca Asocio Tutmonda (Universal Stateless Association).
'The International' was the most important song of the socialist movement, sung millions of times. The text was written by Eugene Pottier in commemoration of the repression of the Paris Commune of 1870-1871. It starts with the famous phrases 'Arise, ye prisoners of starvation, Arise, ye wretched of the earth'.