February has a way of thinning the ranks. It sits awkwardly in the calendar, shorter than it ought to be, often colder than expected, and in the war years it carried a particular weight for the men of the Silent Service. The United States Navy submarine force never occupied much physical space in the wartime Navy. Fewer than two percent of personnel wore dolphins. Yet by the end of the Pacific War, submarines had strangled more than half of Japan’s merchant shipping. That success did not come cheaply. Fifty-two boats did not return. Thirty-five hundred and six men went on what submariners still call eternal patrol. No other branch of American service lost such a high percentage of its own.