British Espionage in Spain during WWII

This document is the identity card of Juan Martínez Martínez, the fictitious name of Lorenzo Sanmiguel, leader of the largest British intelligence network in Spain (the Sanmiguel Network), which covered the entire Cantabrian coast.

In late spring 1940, with the United Kingdom on the defensive after the fall of France, the Iberian Peninsula became a priority target for British intelligence due to its strategic location and the potential threat to Gibraltar, As a result, the British established extensive intelligence networks across the peninsula, along with Special Operations Services groups trained in their country ready to operate especially in key Spanish ports that served as refuges and support points for Axis ships and submarines.

The British also established surveillance and intelligence structures focusing on the transportation of tungsten—a strategic material for the German armaments industry—and maritime traffic. Their work intensified after the United States entered the war. The British also created the first European military resistance unit of maquis, the León-Galicia Guerrilla Federation, which was to act if Franco formally joined the Axis. Finally, they bribed several Spanish generals to use their influence to keep Spain neutral in the war.

The role of the Iberian Peninsula changed after the Allied landing in North Africa in November 1942 and the August 1943 agreement with Salazar which allowed the Americans and British to use bases in the Azores. All of this, along with U.S. pressure on Britain to force Franco out of power, led to the ultimatum demanding that he reverse his pro-German policy that British ambassador Samuel Hoare delivered to the Spanish dictator during an urgent visit to the Pazo de Meirás, where Franco was vacationing, on the 20th of that month. Then, instead of returning to Madrid, Hoare left for London without setting a return date, triggering the greatest crisis in bilateral relations to that point.

The threats had an effect, but Franco used the discovery of the Sanmiguel network that summer—thanks to Gestapo intelligence—to strengthen his negotiating position. The agreement with Britain allowed its intelligence services to continue operating in Spain as long as they did not work against the regime. From that point on, Allied pressure on the dictatorship eased, allowing Churchill to gradually adapt his rhetoric and moderate his policy toward the Spanish regime from mid-1944 onward. As a result, the Allied armies began their advance across continental Europe following the Normandy landings, the role of the Iberian Peninsula—and therefore that of potential resistance and espionage networks—became secondary.

EGS