No Room for Mistakes - British and Allied Submarine Warfare 1939-1940, Geirr H Haarr.
An excellent detailed history of Allied submarine warfare during the
first sixteen months of the Second World War, a period of dramatic
changes in the situation at sea, in which the British submarine service
had to find a suitable role and absorb heavy losses, while coping with
the Norwegian campaign and the sudden expansion of their duties after
the Fall of France.
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