In July 1247, King Ferdinand III of Castile began a prolonged siege of the city of Seville, one of the most important Muslim cities in the Iberian Peninsula. The siege lasted over a year, with Castilian forces blockading the city by land and a fleet of ships preventing supplies from reaching it via the Guadalquivir River. The siege culminated in the city's surrender in November 1248, a major victory for the Reconquista.

The fall of Seville was celebrated in numerous chronicles and ballads, becoming a defining moment in Spanish literary history. The siege and its outcome are commemorated in the epic poem Poema de Alfonso Onceno, which recounts the deeds of Ferdinand III. This event also fueled the development of the romance tradition, a genre of narrative poetry that often drew on historical events and heroism, shaping the cultural identity of Spain for generations.