The First Siege of Gibraltar was part of the wider conflict known as the Reconquista, where Christian kingdoms sought to reclaim territory from Muslim rule in the Iberian Peninsula. The siege initiated in September 1309 under the leadership of Alfonso Pérez de Guzmán, a prominent Castilian noble. The Kingdom of Castile aimed to seize Gibraltar, which held immense strategic value due to its position at the gateway to the Mediterranean. The Emirate of Granada, led by its ruler, fought to defend this key outpost against the advancing Castilian forces.

The siege unfolded over several weeks, as the Castilian troops employed various tactics to overcome the defenses of the city. The culmination of this military effort resulted in the successful capture of Gibraltar, marking a significant setback for the Emirate of Granada. This victory not only bolstered the military reputation of Castile but also demonstrated the effectiveness of their siege warfare techniques, which would be further refined in subsequent conflicts.

The implications of the siege extended beyond immediate military gains, as it contributed to the gradual decline of Muslim political power in southern Spain. The capture of Gibraltar allowed Castile to secure control over the strait, enhancing maritime trade and military logistics. Furthermore, it set a precedent for future sieges in the region, demonstrating the effectiveness of coordinated Christian efforts against Moorish territories in their quest for reconquest.