In 1924 he joined the Union of Bricklayers in Madrid, and in 1932 became a member of the Spanish Communist Party (Partido Comunista Español, PCE).

In the Spanish Civil War he fought on the Somosierra and Guadarrama fronts, and in the headquarters in Montaña, Getafe and Cuatro Vientos.

[4] In March 1939 Segismundo Casado launched an anti-communist uprising in Madrid supported by the militant anarchist Cipriano Mera.

[1] Two South American activists were arrested in Madrid in September 1941, Eleuterio Lobo Martín ("Leandro") and Mari Ibarra ("Sionin").

[1] Isidoro Diéguez Dueñas was executed by firing squad against the wall of the East Cemetery in Madrid on the morning of 21 January 1942.