Biscay Campaign

The Biscay Campaign (Campaña de Vizcaya) was an offensive of the Spanish Civil War which lasted from 31 March to 1 July 1937. 50,000 men of the Eusko Gudarostea met 65,000 men of the insurgent forces. After heavy combats the Nationalist forces with a crushing material superiority managed to occupy the city of Bilbao and the Biscay province.

Background
On 22 March 1937, Franco decided to halt his offensive against Madrid and start an offensive against the northern Republican held zone. The northern zone was politically divided and isolated from the central Republican zone. Furthermore, there was most of Spanish iron and coal and the chemical plants of Biscay. The Nationalists decided to start the occupation of the northern Republican zone with the conquest of the Biscay province.

Opposing forces
The Nationalists had the Emilio Mola's Army of the North (55,000 men). The Nationalist attack started with the Navarrese Division, led by the General José Solchaga. This division had four brigades led by the Colonels Garcia Valiño, Alonso Vega, Cayuela and Latorre (18,000 men) and the Black Arrow division (8,000 men with Italian officers). This force was established between Vergara and Villareal, on the border of the Biscay province. The Nationalist had also 200 guns, 120 aircraft, the battleship España, the cruisers Canarias and Almirante Cervera and the destroyer Velasco.

Opposing them, the Republicans had the Llano de la Encomienda's Army of the North, theoretically numbered 150,000, but there were no unity between the Basque Nationalists, the Asturians and the Santaderinos. The Basque Army in Biscay had 30,000 men (most of them Basque Nationalists and also Asturians). The Republicans also had 140 guns, 25-30 aircraft, two destroyers and three submarines.

The Offensive
The Nationalist offensive started on March 31, and Mola threatened to bomb the Basque cities and industries:"I have decided to terminate rapidly the war in the north: those not guilty of assassinations and who surrender their arms will have their lives and property spared. But, if submission is not immediate, I will raze all Vizcaya to the ground, beginning with the industries of war.". The same day the Legion Condor bombed the town of Durango, there were 250 civilian deaths. On April 1, the Colonel Camilo Alonso Vega captured the mountains of Maroto, Albertia and Jarindo, and the Navarrase troops attacked the town of Ochandiano and encircled the Basque troops in it. The Navarrese occupied the town on April 4, after heavy combats and aerial bombardment. The Basque troops left 400 deaths and 600 prisoners. Then Mola, decided to stop the advance due bad weather.

On April 6, the Nationalist government in Burgos announced the blockade of the Basque ports. The British government said that the blockade was effective and warned British ship not to go to Bilbao. Nevertheless, British merchants broke the blockade and entered in Basque ports. On April 20, the Nationalists continued their offensive after a heavy artillery bombardment. The Basque troops led by the major Pablo Belderraín tried to resist but the 1st Navarrese Brigade led by the colonel Garcia Valiño broke the front and occupied Elgeta. The same day the Legion Condor bombed Guernica. The Basques retreated to the Iron Belt line and the Legion Condor bombed the roads and woods with incendiary bombs. Then, the Lendakari, Jósé Antonio Aguirre, decided to assume the command of the Basque troops, due the incompetence of Llano de la Encomienda. On April 30, the Italians occupied Bermeo, but the Nationalist battleship Jaime I, was sunk by a mine.

The fall of Bilbao
The Republican government tried to send fighters to the Basque country across France, but the French government returned the aircraft after confiscate its machine guns. The commander of the FARE, Hidalgo de Cisneros, decided to send 50 fighters and bombers to the Basque country, across the Nationalist held territory, 45 reached Bilbao. Meantime, the bad weather stopped again the Nationalist offensive, a new shipment of weapons (55 antiaircraft guns, 30 cannons and two squadrons of Chatos), reached Bilbao, and the General Gamir was sent to Biscay in order to organize the defense of Bilbao and to replace Llano de la Encomienda. The Republican government launched two offensives in Segovia and Huesca to halt the Nationalist offensive against Bilbao but both failed.

Mola died on June 3 and was replaced by General Davila. On June 11 the Nationalist troops reached the Iron Belt and on June 12 after a heavy aerial and artillery bombing (150 guns and 70 bombers) the Nationalist troops assaulted it. A Basque deserter, the Major Goicoechea gave to the Nationalist the plans of the Iron Belt. The Nationalist attacked in the Mount Urcullu and broke the Basque lines. On June 14 the Basque government left Bilbao, on June 18 the Basque troops was ordered to leave the city and by June 19 the Nationalist conquered the city.

Aftermath
The Basque autonomy was abolished and the Basque tongue forbidden. Biscay had the only factory in Spain capable of the manufacture of artillery shells and half of the Spanish production of explosives.