Seizing the Enigma (50 page)

ULTRA
had little effect on this. The few U-boats dotting the Atlantic posed little threat. The vast convoys, sometimes of hundreds of ships stretching from horizon to horizon, proceeded majestically across the broad expanse of the Atlantic, guarded by sea and by air, bringing the men and materiel that would drive a stake through the heart of the wickedest regime the world had ever seen. With the help of
ULTRA
, the Battle of the Atlantic had been won.

U
LTRA WAS THE GREATEST SECRET OF
W
ORLD
W
AR
II
AFTER THE
atom bomb. With the exception of knowledge about that weapon and the probable exception of the time and place of major operations, such as the Normandy invasion, no information was held more tightly. Churchill’s anxiety about the secrecy of
ULTRA
was constant; rules in all of the armed forces forbade any action to be taken on the basis of Enigma intercepts unless some cover, such as air reconnaissance, was provided. The security implies
ULTRA
’s significance.
ULTRA
furnished intelligence better than any in the whole long history of humankind. It was more precise, more trustworthy, more voluminous, more continuous, longer lasting, and available faster, at a higher level, and from more commands than any other form of intelligence—spies or scouts or aerial reconnaissance or prisoner interrogations. It thus fulfilled better than ever before intelligence’s ultimate purposes, one in the psychological component of war, one in the physical. It improved command, and it magnified strength.

It improved command by reducing much of the uncertainty surrounding the enemy. As one scholar has written, “
ULTRA
created in senior staffs and at the political summit a state of mind which transformed the taking of decisions. To feel that you know your enemy is a vastly comforting feeling. It grows imperceptibly over time if you regularly and intimately observe his thoughts and ways and habits and actions. Knowledge of this kind makes your own planning less
tentative and more assured, less harrowing and more buoyant.” This benefit of Enigma solutions was intangible but real.

ULTRA
magnified strength in the sea war in several ways. It enabled the Allies to steer the escort-carrier hunter-killer groups toward their prey instead of having to search a large area for them. In sixty days in July and August 1943, when a daily average of fourteen U-boats dotted an area the size of the United States west of the Mississippi, those task forces made forty attacks, sinking thirteen submarines. Since with each attack the task force had found a few U-boats in an oceanic waste the size of Texas, it was doing work that without
ULTRA
would have required many more task forces. Likewise, a U-boat whose location had been revealed by
ULTRA
within the previous five days was three times more likely to be sunk than one not so compromised. Thus did
ULTRA
focus the anti-U-boat efforts and so greatly increase their efficiency.

Defensively,
ULTRA
magnified strength relative to the enemy by depriving him of his powers. Steering a convoy around a wolfpack meant that the U-boats could not attack it, thus in effect adding convoy escorts and retaining ships that it would otherwise have lost. Though the value of
ULTRA
as convoy defense cannot be quantified as precisely as with the offensive operations, some conclusions can be drawn.

When naval
ULTRA
was current, U-boats contacted only two-thirds as many convoys as during a blacked-out period. And the rate of sinking of merchant ships in an operational area when
ULTRA
was current declined to one-sixth of that during a blacked-out period. A comparison on a different basis between
ULTRA
and non-
ULTRA
periods concluded that Enigma solutions saved between 1.5 and 2 million tons of shipping in the last half of 1941 and more than 650,000 tons in the first five months of 1943.

So, did
ULTRA
win the war?

Some writers claim that it did. But even as hyperbole this is nonsense. The Allies would have won without it—though at a much greater cost in men and materiel. Some historians argue that “Without
ULTRA
… the Allies could not have won the Battle of the Atlantic.” This too exaggerates. So does the view that
ULTRA
stands “at the top” of the factors that influenced the outcome of the Atlantic battle. The most important factor was the construction of an unbelievable number of vessels by American shipyards—so many so fast that even the total effort of all Dönitz’s U-boats was doomed to ineffectuality. Also more important than
ULTRA
was air cover, which drove the U-boats under water and thereby slowed them so that they could not keep up with the convoys.

What effect, then, did
ULTRA
have? Can it at least be estimated how many months of war the solving of the naval Enigma saved?

Any answer must be hypothetical, and similar calculations could be made about any wartime activity. Nevertheless, it is illuminating to suggest a figure. Without the shipping saved by
ULTRA
, forces would have been withdrawn from the Pacific to attempt to keep to the timetables for the invasions of Sicily and Italy and, above all, of Normandy. Calculations of ship production and of logistic problems suggest that these invasions would have been delayed by about three months. In particular, the great assault on Normandy might have taken place, not in June 1944, but in the fall, or possibly not until the spring of 1945. During this delay, Hitler’s V-weapons would have caused far greater devastation. The additional submarines that would have come into service would have made crossing the Atlantic and supplying the Soviet Union even more costly in ships and men. The Allied offensives would have come later and perhaps less strongly. The war in Europe might have been prolonged for one year, and because of the withdrawal of forces and supplies from the Pacific to the European theater, the entire conflict might not have ended until 1947. So, taken in isolation, it may be concluded that
ULTRA
saved the world two years of war, billions of dollars, and millions of lives.

But events do not occur in isolation. Even if the codebreakers of Hut 8 and OP-20-G had been totally ineffective, even if the war had been prolonged three months or even more because of their inability,
something entirely external to them would have taken control of events: the atom bomb. If Germany had continued fighting into the summer of 1945, the first nuclear weapon would probably have exploded not over Hiroshima but over Berlin. And the war would have ended then, no matter what the codebreakers had done, or had not.

To anyone who looks back at the German navy’s use of the Enigma machine, one question screams out: if the Germans feared that the Enigma was being solved, why didn’t they change to another cipher machine? The answer, upon reflection, is simple. They didn’t have another machine. Should they have prepared one? With hindsight, one can say yes. But several factors stopped them. The rotor principle offered the most secure practical cipher system then known. No other mechanism matched it. The Germans could have adopted a machine similar to the rotor devices of Britain and America, which used five or even ten rotors at a time, and which stepped them in a far more complex motion than the Enigma’s odometer-like regularity. They failed to adopt such a machine for two reasons.

First, they did not face the reality that Enigma could be broken. The Enigma was an excellent machine, and it was embedded in an excellent web of safeguards against loss, error, and cryptanalysis. The German communications security specialists saw no way that it could be broken. Though they certainly realized that cribs could be used to test for keys, they believed that the vast number of keys defeated this method in practice. They failed to imagine that scores of speedy, brute-force codebreaking machines might be used; their own few cryptanalytic mechanisms were much more primitive. Though the chief judge of the machine’s invulnerability, cryptanalyst Wilhelm Tranow, was not biased in its favor (he had once even urged abandoning the Enigma in favor of a codebook and superencipherment), the officers who did support it would have found it difficult to admit to themselves, to Dönitz, and to Hitler that the system was not invulnerable, as they had repeatedly said it was, and that a new one would
have to be created. Finally, because the Germans never had irrefutable evidence of the enemy’s success in cryptanalysis, they never had to concede that the Enigma was broken. That documents were taken from the weather ships never crossed their minds. With the modifications made to accommodate the growing traffic, they viewed the machine as secure. A new machine was not necessary. Indeed, during the entire war, the Germans never even changed the wiring of the Enigma rotors.

The second reason for not abandoning the Enigma in favor of a new machine was that they had invested too much in the older one. They had bought many machines, distributed them widely, and trained many men in their use. To invent a new system, design a mechanism for it, test a breadboard model, produce thousands of copies, get them to ships (some of them on long patrols), and to shore stations, teach men to use them, and then put them all into service simultaneously, with the inevitable blunders that would call down the wrath of fighting admirals and generals—this was unthinkable.

Thus the Germans stayed with the Enigma. But explaining why they did so does not tell why the Allies proved superior to the Germans in codebreaking.

Perhaps the most important reason was that the Allies, as Poland was before the war, were on the defensive at first. And the defense requires intelligence. Clausewitz defined the characteristic feature of defense as “awaiting the blow.” An army awaits a blow only if it believes that a blow is planned, and such a belief exists only through information about the enemy. The offense, on the other hand, is “complete in itself,” Clausewitz said. An attacking army need not even know where the enemy force is: it can march about, imposing its will, until it meets its foe. An aggressor nation will put more of its energy into men, tanks, ships, planes, and guns and less into intelligence, one form of which is codebreaking.

A nation that believes it will be attacked will learn what it can about the enemy’s intention. Thus Poland’s fear in the 1920s of German
revanche, touching Poland’s very existence as a state, spurred her efforts to solve the Enigma. She established courses in cryptology. Rejewski, perhaps driven by the same patriotic concern, exerted the extra effort that produced his magnificent solution. This is what the Pole Langer meant when, seeking to ease the embarrassment of Bertrand, who had to admit that France had not been able to crack Enigma, he said courteously, “You don’t have the same motivation as we do.”

The same defensive concerns compelled the Allies to put better men into cryptology than the offense-minded Germans did. In Poland, the Biuro Szyfrów, looking far down the road of cryptanalytic need, hired mathematicians. In Britain, Cambridge students and graduates were the cream of the nation, and G.C.&C.S. took the cream of that cream. In the United States, the draftees who scored the highest on an IQ test were proposed for cryptologic work. But in Germany, no such recruiting seems to have taken place; the Germans, on a blitzkrieg of conquest, seemed not to feel that they needed codebreakers badly. With one or two exceptions, they brought in mathematicians for cryptanalysis only later, during the war. So their agencies, despite individually bright men, did not perform as well as did the Allied units.

The leaders of Britain and Germany personified these differing behaviors. Churchill eagerly read the intercepts and encouraged his cryptanalysts to continue laying their golden eggs. Hitler, although he accepted intercepts, never visited any of his cryptanaltic agencies, never thanked them, and never showed any special interest in their output. In part this difference stemmed from the two nations’ different immediate needs: for a long time, Churchill had little more than intelligence, while Hitler was conquering Europe. In part it was a matter of background: Churchill had for decades dealt intimately with the results of codebreaking, Hitler had never done so. And in part it reflected long-standing national policies. Britain’s maintenance of the balance of power is a reactive or defensive technique that requires intelligence to succeed. Germany utilized the strategic offensive to resolve her problems of indefensible borders and severe
domestic tensions. But this does not call for intelligence, and so her leaders interested themselves in it less than Britain’s leaders did.

Another basic reason for the superiority of Allied cryptanalysis lay in the rule of law. This proved more efficient than a dictator’s whims. Agreement on impersonal norms permitted both Britain’s and America’s high commanders to centralize and rationalize their cryptologic efforts instead of competing for the power that knowledge confers. At Bletchley, the concentration of effort let the various huts share knowledge and bombes and find kisses. In Washington, the army and navy, despite some friction, divided up their work. In Germany, on the other hand, seven major codebreaking agencies continued to work separately at least in part because the organizations of which they were part—among them the army, the Armed Forces High Command, the Foreign Office—were fighting for access to Hitler. He wanted that arrangement because it remitted power to him. But this fragmentation spread cryptanalytic manpower very thin and deprived the agencies of the benefits of cooperation. Parliamentary authority, more rational, prevented such a situation from arising in Britain or the United States.