Axis naval co-operation started after the signing of the Pact of Steel in June 1939 with meetings in Friedrichshafen, Germany, and an agreement to exchange technical information. After the Italian entry into the war and the Fall of France, the Italian Royal Navy established a submarine base at Bordeaux, which was within the German occupation zone. The Italians were allocated a sector of the Atlantic south of Lisbon to patrol. The base was opened in August 1940, and in 1941 the captured French passenger ship was used as a depot ship before being returned to the Vichy French Government in June 1942. Admiral Angelo Parona commanded the submarines at BETASOM under the operational control of "Konteradmiral" (Rear Admiral) Karl Dönitz. Dönitz was the "Commander of the Submarines" ("Befehlshaber der U-Boote") for the German "Kriegsmarine". About 1,600 men were based at BETASOM.