Evacuees and the causes for German naval attacks on civilian ships during World War II
Iron Coffins: A personal account of the German U-boat battles of World War II
...The crucial importance of the U-boat Force is unmistakably clear. Whether or not Germany could have won the war, she was certain to lose it if the gigantic production of American factories reached England in sufficient quantity. On this proposition the lines were drawn for the epic "Battle of the Atlantic," in which the U-boats served as the vanguards of Germany's defense....(p. xiii)
The first year of the U-boat war was extremely rewarding for Germany. Though the Force lost 28 boats, it destroyed one British aircraft carrier, one battleship, five cruisers, three destroyers, two submarines and 438 merchant vessels totaling 2.3 million grossweight tons. Moreover, in the summer of 1940, after the surrender of France, our U-boats were gradually relocated southward to France ports on the Bay of Biscay. This move shortened our routes to and from the Atlantic and signaled a new phase of the war at sea - the great battles of the convoys.
Simultaneously, Admiral Karl Doenitz, Commander-in-Chief of the U-boat Force as of 1935, launched an ambitious program to construct the largest fleet of submersibles that the world had ever seen. The most advanced U-boat of that time, Type VII, became the standard Atlantic U-boat; it had a displacement of 770 tons and a cruising range of 9,000 nautical miles. In the course of the war, 694 boats of this type were built and up-dated periodically with new improvements; they accounted for 90 per cent of Allied shipping losses.
Great Britain soon felt the sting of this stepped-up building program. Unrestricted U-boat warfare against the North Atlantic convoy routes resulted in the destruction of 310,000 tons of shipping in one four-week period in the fall of 1940. (p. xiv)