The problem of how to defend the myriad of shipping assets that must transit in and out of shallow water in time of war has plagued naval planners since World War I. Whether it be the delivery of materiel to ports or the opposed amphibious assault in a hostile environment, the successful completion of nearly every naval evolution terminates in shallow or restricted waters of some type. It is in these waters that the advantages of conventional submarines outweigh the advantages of nuclear-powered ones and any disadvantages of the former are reduced.
O'Keefe, James G.
"Muddy Waters and the Iron Depth Charge,"
Naval War College Review: Vol. 37
, Article 3.
Available at: http://digital-commons.usnwc.edu/nwc-review/vol37/iss1/3