Italian submarine service very limited operational due to heavy losses, lacking fuel oil and so on in September 1941

Marcello-class. Warshipsresearch.blogspot.com

American naval attaché at Rome, Italy reported in September 1941 that the Italian navy was considered to have lost 40 submarines. Based at Bordeaux, France were 9 of the Marcello type, 3 Galvani, 3 Calvi, 1 Archimede, 2 Cappellini, 4 Luizzi, 2 Argo, 2 Gluaco and 5 Marconi excluded Da Vinco and 2 other probably Perla class, totally 33. One source stated at any time just 7 submarines were operating in the Mediterranean. Around 40 others were available but restricked lacking fuel oil and other reasons.

Source

National Archives USA. Record Group 38: Records of the Office of the Chief of Naval Operations. Series: Secret Naval Attaches Reports. Estimate of potential military strength (pt.). Summaries. Reports from London, Paris, Brussels, Rome and Berlin. Roll M975-001.