The outbreak of the Civil War surprised him, as he was spending the summer on the Basque coast. He crossed Republican lines to reach Pamplona to join up with the Nationalist Army of the North, led by Emilio Mola. He commanded several Carlist units, and with the First Navarrese Brigade participated in the campaign of the North. After he was promoted to colonel, he commanded the First Division of Navarre, with which he fought in Teruel and in the campaign of Aragon, along with those of Aranda, to the Mediterranean, thus cutting the Republican zone in two. He also commanded an army corps in the XYZ battle, in the Battle of Ebro and participated in the offensive of Catalonia. He led the Maestrazgo Army in the final offensive of the Spanish Civil War.