After the Civil War started in Spain in July 1936 , both Italy and Nazi Germany supported the Nationalists of General Franco , whereas Soviet Union was actively supporting the Republicans . During the first year of the war , the Soviets used the Republican controlled ports of Bilbao and Santander in the North of Spain adjacent to the French border , but after their fall in the summer of 1937 , the USSR was forced to use ports in the Mediterranean to continue supplying the Republicans . Both Italy and Germany deployed their submarines in the Mediterranean in early 1937 to interdict with Republican shipping , but without much success . On August 3 , 1937 Franco made an urgent plea with Mussolini to use the Italian fleet to prevent the passage of a large Soviet transport convoy , which just departed from Odessa . Originally , only submarines were supposed to be used , but Mussolini was convinced by Franco to use Italian surface ships too against the Soviets . The Italian blockade was put into effect immediately , with two cruisers , and , eight torpedo boats and eight destroyers , including '' Zeffiro '' being deployed in and around the Strait of Sicily and Strait of Messina . '' Zeffiro '' participated in several patrols , which normally lasted three days , often paired with her sister ship , but none of her missions were successful . In September 1937 the Nyon Conference was called by France and Great Britain to address the " underwater piracy " conducted against merchant traffic in the Mediterranean . On September 14 , an agreement was signed establishing British and French patrol zones around Spain ( with a total of 60 destroyers and airforce employed ) to counteract aggressive behavior by submarines . Italy was not directly accused , but had to comply with the agreement and suspend the maritime operations
Nyon Conference
Nyon Conference
Italian destroyer Zeffiro (1927)