On September 5, 1936, Nationalist forces under Colonel Beorlegui captured the Basque city of Irún, near the French border, after a fierce battle that cut off the Republican north from international supply routes. The fall of Irún allowed the Nationalists to isolate the northern Republican zone and was a severe blow to the Basque resistance. The city's defenders, mostly Basque nationalists and anarchist militiamen, fought bravely but were overwhelmed by the Nationalists' superior artillery and air support.

The fall of Irún inspired a wave of Basque nationalist poetry, with writers mourning the loss of the city and calling for continued resistance. The event also featured in the war poetry of international volunteers, who saw the battle as a symbol of the Republic's desperate struggle. The poetry of the Basque front, written in both Basque and Castilian, reflected the unique cultural identity of the region and its determination to resist Franco.