On February 13 the battalion left Basauri to fight in Asturias, within the 1st Basque Expeditionary Brigade. Between February and March, it participated in the Siege of Oviedo, in the San Claudio sector. The battalion achieved its objective but had to fall back before the failure of other republican units. The battalion then returned from Asturias to stop the enemy offensive, acting from the top of Barazar.