Ordered right after World War One, the S-Class was the last US submarine class to be given numerical designations instead of names and to retain them. In this case, the designation was an S followed by a number issued in the succession of commisioning of these vessels.

    Utterly obsolete as these vessels were by 1941, they scored remarkable successes - in fact, their 1942 operations accounted for the largest Japanese warship sunk to that date by submarines, the cruiser Kako.  
Their design had been one of the Bureau of Construction and Repair, the first instance in which a submarine was designed by this office. The S-Class succeeded the R-Class, improving almost every respect of the latter, including duration, number of reserve torpedoes and size.

    By 1943, all S-Class submarines had been removed from service in the US Navy, or delegated to secondary patrol duties in the North Pacific. The Royal Navy received four of the submarines, which were put to some use in the Mediterranean.  
Of the remarkable actions of these tiny boats, only the above mentioned sinking of Kako, on 10 August 1942 off Kavieng in the New Britian archipelago, by S-44, is remembered vivedly. Minor actions were also conducted by these boats in support of the Philippines and the ABDA naval forces.