The Santoña Agreement of August 24, 1937, marked a pivotal moment in the Spanish Civil War as the Basque Army capitulated to the Italian Corpo Truppe Volontarie. This document was the product of dire circumstances faced by the Basque defenders, who were struggling against a well-coordinated Francoist campaign supported by Italian troops. Under increasing pressure, the leaders of the Basque Army recognized the futility of continued resistance and sought to negotiate terms that would allow for the safety of their forces and civilians. The terms provided for the evacuation of Basque fighters who chose to leave rather than fight against Franco's troops.

The agreement led to significant territorial and military shifts in the Civil War, allowing the Italians to gain control over key areas of northern Spain, including the Basque Country. This expanded Italian influence and prestige at a time when they were heavily involved in supporting Francisco Franco's nationalists. Although the agreement was initially seen as a way to protect Basque civilians and military personnel, it ultimately represented a tactical defeat for the Republican side, paving the way for further nationalist advances.

The surrender further weakened the Republican forces and contributed to their eventual downfall in the broader context of the Spanish Civil War, highlighting the volatile alliances and the impact of foreign intervention. The aftermath of the agreement left a lasting legacy on the Basque region, sparking debates on national identity and regional autonomy that would resonate in Spain for decades to come.