In the early months of the Spanish Civil War, Republican forces and militias carried out a wave of anti-clerical violence, killing thousands of Catholic clergy, nuns, and religious brothers and burning churches and monasteries. The violence, which was particularly severe in Madrid, Barcelona, and other Republican-held cities, was a response to the Catholic Church's close association with the conservative and monarchist forces that had opposed the Republic. The attacks deeply shocked international opinion and provided a powerful propaganda weapon for the Nationalists.

The anti-clerical violence was condemned by many Catholic poets, who wrote verses mourning the martyrs and defending the Church. The violence also inspired a number of poems by Republican supporters, who justified the attacks as necessary acts of revolutionary justice. The controversy over the anti-clerical violence also deepened the divide between Catholic and secular poets, a division that would persist throughout the war.