Spanish Civil War: Madrid's Defense and Northern Campaigns
The Battle for Madrid: 1936-1937
The Spanish Civil War did not begin as a confrontation between two traditional armies. Instead, the military organization had been dissolved and replaced by popular militias. In Catalonia, volunteers were enlisted in columns with the intention of recovering the Aragonese capital, without success. The failure to recover Mallorca provided a crucial platform for Fascist aviation.
Meanwhile, Nationalist forces, led by General Yagüe, were able to overcome Republican resistance in Badajoz. In the North, General Mola had conquered the area stretching from San Sebastián and Irún towards the center. Franco, after the relief of Toledo on October 1st, advanced to the gates of Madrid.
In Madrid, from October 29th, the population was mobilized with the cry of "¡No Pasarán!" (They Shall Not Pass!), enduring bombings by the Condor Legion and repelling the insurgents. The Republican government, located in Madrid, moved to Valencia on November 6th, leaving the city in the hands of the Defense Junta. The arrival of the International Brigades and the Durruti Column aided the defense. Franco, unable to take Madrid in December, decided instead to isolate it from the rest of the Republic.
The Battle of the North: 1937-1938 Campaigns
Franco's strategy to isolate Madrid led to the battles of Jarama (February 1937, Madrid), which had an uncertain outcome, and the Battle of Guadalajara (March 1937), where the Republican triumph weakened the Fascist pressure on the capital.
Franco then shifted the focus of the war to the North, initiating the attack on Biscay at the end of March, led by General Mola. Guernica, on April 26th, was ravaged by Nazi aircraft under Franco's orders. Bilbao was occupied in June. Meanwhile, Republican forces attacked Brunete and Belchite, but these efforts were unsuccessful as Franco maintained pressure on Santander and Asturias. The occupation of the North was completed in October 1937, giving the Nationalists control of a mining and industrial area of prime importance. Thousands of people fled, many seeking refuge in Catalonia.
During this period, the Popular Army was formed, and the militias were disbanded. The new army was organized into corps, divisions, and brigades, with its command passing into the hands of military professionals. This reorganization led to tensions; anarchist sectors and the POUM regarded the decision as a betrayal. However, the Republican administration viewed it as the only means of effective resistance against Franco's relentless war.
In December 1937, Vicente Rojo assumed command of the Republican plan for the Battle of Teruel. This was an initial success, but a harsh Nationalist counter-offensive in February 1938 forced Republican troops to evacuate the city.