ROBERTS | 169
Those were the people at one end. People at the other end included the generals and field
marshals in charge of the fighting forces on each of the battlefronts, people like von Weichs,
von Kluge, and Model, who headed up the three Russian sectors. We covered the five main
battlefronts. There were the three Russian fronts: north, central, and south. Then there was the
front in the west, and the front in the Italian Peninsula, important because the Germans moved
their troops to Sicily when they were routed out of North Africa by Montgomery.
Army Enigma at that stage dealt with divisions and regiments, whereas Tunny dealt with
whole armies and army groups. As you can imagine, then, Tunny continuously produced a very
high grade of intelligence.
Our best successes
There are many situations in which our ability to break Tunny played a major role, but there
are four absolutely outstanding examples. First and foremost there was D-Day, the Allied land-
ings on the beaches of Normandy, in June 1944. In the run-up to D-Day it was important to
know whether the Germans were going to keep their large Panzer divisions further north in the
Calais–Boulogne region, which was what Hitler wanted, or whether they were going to move
them to Normandy, as the generals wanted. The generals were the professionals and they knew
that the Allies needed good landing beaches—but Hitler was the boss. In fact, we helped him
to make the wrong decision: one of our clever tricks, in this period before D-Day, was to moor
objects along the Kent and Essex coasts that looked from the air like a large number of landing
craft, poised for an invasion in the Calais–Boulogne region.
Hitler fell for it. Through Tunny decrypts we knew that his assessment of the situation had
prevailed, and that Normandy would therefore be more lightly defended than if the generals had
had their way. Moreover our decrypts told us the location of pretty much every Panzer division
in the area. You can imagine how much help all this gave Eisenhower and Montgomery, when
they and their staff were planning the invasion. If, on the other hand, Hitler had made the oppo-
site decision, and moved all those tanks and men down to Normandy, then there would have
been a good chance that the D-Day landings would have failed, and then it would have taken at
least two years to mount another similar effort—during which time Hitler could well have made
Europe impregnable. Not only that, but his scientists were working on their own atom bomb,
and had brought together 25% of the uranium needed. It was an absolutely critical time.
The second outstanding example of how Tunny decrypts turned things our way was the great
tank battle near the Russian city of Kursk. The Germans, always short of petroleum, had made
an enormous effort to get at the Russian oil fields, but in February 1943 they were badly defeated
at Stalingrad. Then, in April 1943, we broke Tunny messages revealing that the Germans were
planning another assault, a huge one, at Kursk, southwest of Moscow. We gave the Russians
months of advance warning, and they used that time wisely, including putting pressure on their
factories to turn out more tanks. Eventually the Battle of Kursk began on 4 July 1943, and the
Germans were defeated in the biggest tank fight ever to take place.
The third outstanding example was the German defeat in Italy. Once the German Army,
retreating from North Africa, had been driven out of Sicily, it moved to the Italian mainland.
Here Kesselring, the German supreme commander in the Mediterranean region, mounted a
very stubborn defence. But we broke a large number of Tunny messages to and from Kesselring,