The Biscay Campaign (Spanish: 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.