outstanding war service under the most difficult conditions. Indeed, there is some justification for describing them as the most important of all the Royal Navy's submarines in the pre-missile era.
IMPROVED S CLASS SUBMARINES
Fifty Improved S Class submarines were launched between 1940 and 1945, making the S Class the largest single group of submarines built for the Royal Navy, a total of 62 being constructed over a period of 15 years. In one respect, the S Class was unique in that they were the only class to remain in production throughout the war period - which is a fair measure of their success.
