The Nationalists returned to focus on the capture of northern Spain. German test aircraft, with latest models, faced an outdated Basque air force, although it did have some Russian planes. Heavy aerial bombardment from 200 Nationalist, German and Italian planes was used far behind Basque lines in August 1937, leading to the fall of Santander after the Battle of Santander on 1 September. The formal battle in Asturias ended with the fall of Gijon on 21 October. A large amount of ammunitions had been used by the Legion, including a million machine gun rounds and 2,500 tonnes of bombs. Germany immediately began to ship industrial production back to Germany. Sperrle argued repeatedly with Faupel, and against HISMA's monopoly. Faupel was replaced by Franco, through Sperrle. Sperrle also returned to Germany and was replaced by ; following disagreements with Volkmann, Von Richthofen would be replaced with Hermann Plocher in early 1938.