MTB in the Strait of Messina

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S.Morison (Sicily - Salerno - Anzio, January 1943 - June 1944, р.213) writes that "the night of 11 August 1943 three MTB  torpedoes and artillery attacked the six small Italian ships, chased them to Messina and one knocked out." It was the only time when the British were trying to disrupt the operation «Lehrgang». What MTB and what Italian ships took part in action?