The Ba.65 debuted during the Spanish Civil War. Thirteen Series I aircraft, powered by the Gnôme-Rhône engine, equipped the 65a "Squadriglia" of the "Aviazione Legionaria" (Legionary Air Force). The unit took part in operations at Santander in August 1937, then at the battles of Teruel and the Ebro. The aircraft proved effective and was compared positively with the German Junkers Ju 87 "Stuka". In a unique engagement, one of the Legionary Air Force pilots scored an air-to-air victory when he encountered a lone twin-engine Tupolev SB bomber over Soria and shot it down. Of the 23 Ba.65s sent to Spain, 12 were lost in the course of the civil war. They flew 1,921 sorties, including 368 ground-strafing and 59 dive bombing attacks. When the "Aviazione Legionaria" returned to Italy in May 1939, they transferred their 11 surviving Ba.65s to the Spanish Air Force.