Manuel, his younger brother, and their mother put their possessions in a small covered cart and walked with it to live in Madrid.

Protected by the 1869 Constitution, the Spanish section of the International Workingmen's Association (AIT) organized a series of conferences in Madrid.

The appearance of Solidarity, newspaper of the International, started him on the intense journalistic career that occupied the rest of his life.

On 22 May 1879, at a renowned clandestine banquet of international brotherhood in Madrid, twenty-five people (led by Iglesias) founded the Spanish Socialist Workers Party (PSOE - Partido Socialista Obrero Español).

On 12 August 1888 the Spanish General Workers Union (UGT) was founded in Barcelona, its name proposed by Iglesias.

Republicans had opposed Iglesias, but a Republican-Socialist alliance paved the way for the 1910 elections to make him the first socialist deputy in the Spanish Parliament.

[citation needed] Characterised by vehement defense and furious attack, his works make an ethically coherent call for regeneration and hope.

On his death, an office drawer contained a parting gift of 1,000 pesetas from Iglesias for The Socialist, to which he had been linked from its birth.