By January 1942 many MAS boats were worn out or in need of refit, but losses had been quite light and the Regia Marina's Chief of Staff, Admiral Arturo Riccardi, could easily accept a German request made that month to deploy Italian coastal forces to the Black Sea.

[2] The Russian expeditionary force consisted of the IV Flottiglia, MAS 566-575 under Commander Francesco Mimbelli, who had distinguished himself with his torpedo boat Lupo during the battle of Crete in 1941.

Six midget submarines (CB 1-6), a Squadriglia of five MTSM attack craft (an enlarged and improved hull version of the earlier MTs, 8.3m long with two engines, one torpedo and better sea-keeping characteristics) and five explosive boats made the journey in the same fashion.

[5] At dawn on 18 June, after an hour long engagement, MAS 570 and 571 led by Mimbelli sank two Russian launches full of troops.

[5] The Italian MAS also acted as a flank force in support of army operations off Sevastopol and Novorossiysk and, despite their obvious vulnerability, they captured more than a thousand Soviet troops during the course of their campaigns.

[5] The last units with Italian crews that continued to operate in the Black Sea were the five CB midget submarines, which, from the new Sevastopol base made, from June to August 1943, other 21 missions.