The Mk 10 torpedo, designed for the R- and S-class submarines, was first introduced in 1915, and had been developed by the Newport Torpedo Station and Bliss in a joint venture. It replaced the earlier Mk 7, and greatly increased submarine torpedo dimensions. 

    The Mk 10 remained the only torpedo suitable to the S-class submarines, their short tubes preventing the use of Mk 14 torpedos. They were not the only submarines to use this weapon, however -- fleet submarines, during the 1942 torpedo crisis, used the Mk 10 as a substitute for the regular Mk 14. A number can be supposed to have been handed over to the British when several S-class submarines were transfered. 

    Despite its age the Mk 10 was the most effective U.S. torpedo of 1941 / 1942, causing the loss of the heavy cruiser Kako off Kavieng on August 9th 1942 as the peak of its career. It was not retained after the production difficulties of the Mk 14 had been corrected.