BATTLE OF THE
The moment England’s supply routes are
severed, she will be forced to
I don’t remember ever having decoded a
message from start to finish to see what
it said. I was much more interested in
the methodology for getting German out
of a coded message.ii
In World War II there was no more vital theatre of conflict than the waters of the Atlantic Ocean, and here, as in every place where the opposing sides sought to outwit each other, the use of codes (and the breaking of enemy codes) was of huge importance to the outcome of the contest. Knowledge of British Admiralty codes initially gave the German U-boats such opportunities for sinking Allied shipping that their crews referred to this period of pre-eminence as ‘the happy time’. Subsequent Allied use of signals decrypted from the German naval Enigma turned the tables completely, making the mid-Atlantic a killing ground for submarines. On this vast ocean, so different from other arenas in which the Allies and the Germans fought, Ultra was as vital as ever. Through their incomplete but decisive mastery of German naval signals traffic, the Bletchley staff enabled Allied armies to cross the Atlantic and the English Channel without hindrance and to take the war on to the European mainland.
By the summer of 1940, German armies had overrun northern and western Europe. The only remaining belligerent, Great Britain, was an island that did not have sufficient food or raw materials to sustain an all-out war effort. Its only recourse was to depend on imports, and the majority of these came east across the Atlantic from Canada and the United States or, in the case of oil, from the Caribbean and the Gulf of Mexico. If the transatlantic lifeline could be severed, even temporarily, by sinking enough of the merchant ships that carried these cargoes, Britain would be unable to carry on fighting. The Germans thus possessed, in their submarine fleet, a highly effective means of defeating Britain quickly and without heavy casualties. Lieutenant Commander DE Balme of the Royal Navy, who was to play a heroic part in the battle, recalled that:
The Germans recognised that the
Atlantic was the vital artery for Britain
to obtain supplies of food (we had let
our agriculture decline between the
wars, so that we could only grow about
one-third of our food), fuel (we had coal
but no oil) and raw materials for our
factories. If they could cut that line,
they could win the war.
The importance of this supply route remained paramount until the end of the European war. It did not matter that America and Russia had now joined Britain in the fight, or that Allied armies were accumulating victories in North Africa, Italy, Eastern Europe or France. Unless the Atlantic shipping routes were secure, Britain would starve and the men and materiel needed to defeat Hitler would not reach the battlefields. It is small wonder that Churchill was to comment:
The Battle of the Atlantic was the
dominating factor all through the war.
Never for one moment could we forget
that everything happening elsewhere,