On December 1936, Prada led a division in the Second Battle of the Corunna Road. In August 1937 he led an Army corps in Cantabria, and on August 29 he was appointed supreme commander of the Republican Army of the North (60,000 men), replacing General Gámir. He tried to reorganize the Republican forces and shot three brigade commanders in order to maintain discipline. However, he could not stop the Nationalist offensive against Asturias and on October 18 he fled from Asturias in order to avoid capture by the Nationalists. On 7 November 1937 he was made commander of the newly-established Andalusian Army, a post he held until 14 March 1938. Following the disaster of the Battle of Merida pocket he was made commander of the Extremaduran Army on 31 July 1938, replacing Colonel Ricardo Burillo who had been abruptly dismissed.