Special Defence Against Aircraft (DECA)

“The problem of the country’s comprehensive defense against the aerial enemy was not addressed, leaving the various active and passive elements that must operate in this kind of war dispersed across different ministries, without unity of training, doctrine, and  - even less - of action.”

With these words, part of a decree of 23 September 1936, Francisco Largo Caballero, the new prime minister of the Republic, described the vulnerable situation in which the country found itself in the face of the use of aviation as an instrument of war. Spain’s neutrality during the Great War deprived it of important lessons offered by the conflict, among them that aviation had changed the rules of war and that the blurry boundaries between civilians and combatants had been dissolved forever.

The aerial attacks experienced during the fateful summer of 1936, together with the arrival of foreign units such as the Condor Legion, soon made it clear that modern warfare required new principles in which anti-aircraft defense was essential. The Republican defensive system initially respected the structure designed in 1935 by the Minister of War, Gil Robles, which was based on the formation of provincial and local Committees in all towns with more than eight thousand inhabitants. These committees remained in place until the end of the conflict.

Efforts were also made to create a comprehensive anti-aircraft defense system that addressed both active defense— with aviation itself as the ‘preponderant element’—and civil protection. Lack of resources and the urgency of the situation led some regions where the coup had failed, such as Barcelona or the Basque Country, to develop their own defensive efforts. Madrid, however, faced the siege of November 1936 practically unprotected, entrusting its air defense to a maximum of three daily aviation patrols.

On 13 March 1937, the anti-aircraft services were reorganized and absorbed by the Ministry of Navy and Air. Four days after Guernica was devastated, on 30 April, a decree created the Special Defense Against Aircraft (DECA), which was integrated into the Undersecretariat of Air under the direct command of the Chief of the Air Force. The photograph, which was most likely staged for propaganda purposes, shows a DECA soldier operating an Oerlikon cannon while an observer scans the sky for enemy aircraft. 

The reform of the defense of towns and cities at the end of June; the declaration of the adoption of civil defence measures as mandatory; the leadership of the DECA, which was elevated to the status of an independent branch in 1938; and the attempts to establish a distinct anti-aircraft doctrine in December 1938 were the milestones that marked the evolution of a framework that never came to be fully deployed before the final collapse of the Republic.

DML