[Young participant in a Holy Week procession, Seville]

[Boy with a cap of one of the metal battalions of the Union de Hermanos Proletarios (Union of Proletarian Brothers), Madrid]

[Republican militiaman saying farwell before the departure of a troop train for the front, Barcelona]

[Women and children saying farwell to Republican militiamen before the departure of a troop train for the front, Barcelona]

[Republican militiaman aiming a rifle, Barcelona or its vicinity]

[Member of the International Brigades, Madrid]

[Republican soldier, Madrid]

[Members of the International Brigades, Madrid]

[Members of the International Brigades, Madrid]

[Member of the International Brigades defending a building in the University City, Madrid]

[Men of the International Brigades in a laboratory of the Medical School building of the University City, Madrid]

[Men of the International Brigades looking out the windows in a laboratory of the Medical School building of the University City, Madrid]

[Member of the International Brigades engaged in house-to-house fighting around the slaughterhouses near the University City, Madrid]

[Member of the International Brigades engaged in house-to-house fighting around the slaughterhouses near the University City, Madrid]

[Member of the International Brigades helping a wounded comrade in the vicinity of the slaughterhouses near the University City, Madrid]

[Republican bunkers around the Clinical Hospital, one of the principal bastions of the Nationalist rebels in the University City, Madrid]

[Republican bunkers around the Clinical Hospital, one of the principal bastions of the Nationalist rebels in the University City, Madrid]

[Building destroyed by Nationalist air raids, Madrid]

[A family portrait and other belongings on the street after an air raid, Madrid]

[Woman after an air raid, Madrid]

[Group of women and children living on the platforms of subway stations in the aftermath of Nationalist air raids, Madrid]

[Amored car used by officers of the International Brigades, Madrid]

[Soldiers reading behind Republican lines, Madrid]

[Crowd watching an air battle over the city, Barcelona]