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How Different Would the World Be Today if Turing Had Not Broken the German Codes?

Editors’ Note: This is the first in a series of four essays, written by Jack Copeland, spotlighting Alan Turing, who is considered the father of modern computing and whose work breaking German codes changed the course of World War II.

Writing ‘counterfactual’ history is always speculative, never cut and dried. Because, if some key matters had gone differently, the overall outcome of a war or battle or election might have been very different or it might nevertheless have been just the same. If the CIA had killed Osama Bin Laden in 2000, 9/11 might still have happened—perhaps because, following Bin Laden’s (counterfactual) death, one of his lieutenants would have stepped forward to take control of Al Qaeda and implement Bin Laden’s plans.

If Hitler’s Operation Sea Lion (Seelöwe)—his planned invasion of Great Britain in 1940—had actually been launched, troop carriers would have poured across the English Channel from France, accompanied by fleets of supply barges loaded with tanks, artillery, and heavy machine guns. During the massive attack by sea and air, thousands of gliders crammed with heavily armed crack German soldiers would have descended onto British soil. Paratroops would also have rained down, with swarms of dive-bombers disabling airfields and holding back a British ground response.

Once the invaders had secured a foothold—a patch of territory containing suitable harbours and airfields—Hitler’s formidable forces would have advanced ruthlessly in every direction, until they held all Britain’s key cities, or so the Führer planned. In the event, though, the Sea Lion invasion was postponed and then abandoned. But Britain’s fate had hung by a thread. If her Royal Air Force had not proved so resilient during the summer of 1940, if the German leader’s attention had not been wandering in the direction of Russia, if Alan Turing’s complicated electromechanical machine or bombe, whimsically named ‘Agnus Dei’—the Lamb of God—had not been breaking the Luftwaffe’s top-secret Enigma communications … then it might all have turned out very differently. When the Imperial Japanese air force attacked Pearl Harbor in 1941, Roosevelt might have faced a Europe completely dominated by Emperor Hirohito’s ally, Hitler.

The tide began to turn against the German military in 1942, with the neutralisation of the North Atlantic U-boat threat, and the humiliating rout of Field Marshal Rommel’s panzer army at El Alamein in North Africa. British successes in the U-boat war—where Turing was a key player—freed up the supply routes from North America to Britain, while the disaster at El Alamein denied Hitler his chance of taking the Suez Canal and capturing the precious middle Eastern oilfields. Debilitating shortages of fuel plagued the German military for the rest of the war.

During the build-up to the fierce fighting at El Alamein, the Bletchley Park codebreakers were reading Rommel’s secret messages. He gave them the welcome news that his tanks had insufficient fuel to fight effectively. The codebreakers themselves had played a leading role in bringing this situation about—for weeks, their decrypts had been unmasking the cargoes of the German and Italian ships carrying Rommel’s supplies across the Mediterranean. This intelligence enabled the RAF to pick and choose the best targets. Thousands of tons of fuel went blazing into the sea. Ten days into the battle, a broken message from Rommel to Berlin confessed that the ‘gradual annihilation of the army must be faced’. Hitler’s response, eagerly read at Bletchley Park, told Rommel not to yield a single step—he must, Hitler ordered, take ‘the road leading to death or victory’.

Suppose, contrary to fact, that Turing and the Bletchley Park codebreakers had not managed to crack the communications of the German and Italian navies in the Mediterranean, and had failed to break the cloaked messages of the North Atlantic U-boats. What would the result have been? The U-boats would certainly have continued to prey with their merciless efficiency on the vast convoys of merchantmen bringing precious food, fuel, munitions, and manpower, from America to Britain. Untold quantities of sorely needed materials would  have plummeted to the bottom of the ocean. Without the RAF’s depredations on his own seaborne supplies, Rommel might even have defeated the British at El Alamein, and gone on to capture the middle-eastern oil for Germany. Yet, even so, the war in Europe might still have ended at more or less the same time that it did—the spring of 1945—because of other counterfactual events.

For example, in 1945 America or Britain might have dropped an atomic bomb on Berlin. Even without a European atomic bomb, and even if, thanks to tighter Axis cipher security, Bletchley Park had not been able to break the key Enigma, Tunny, and Hagelin cipher systems, the Allies might nevertheless still have prevailed. The German defeat might have been virtually inevitable once Hitler took on the vast Soviet Union. Although, in the actual course of events, Bletchley Park decrypts did play a crucial part on the Russian front too—most especially the intelligence wrung out of top-level Tunny messages between Berlin and the front-line generals, by means of a codebreaking method named simply ‘Turingery’ after its resourceful and brilliant inventor.

Can historians quantify Turing’s impact on the course of the war? They certainly cannot claim with any great confidence that what Turing did shortened the war, as the atom bomb example illustrates only too well. But, in the 21st century, we can at the very least give a reasonably complete account of what Turing actually achieved during his years at Bletchley Park—a picture largely denied to 20th century historians, due to the blanketing official security. Building on pre-war work by legendary Polish codebreaker Marian Rejewski, Turing invented the Enigma-cracking bombes that quickly turned Bletchley Park from a country house accommodating a small group of thirty or so codebreakers, into a vast codebreaking factory. There were approximately 200 bombes at Bletchley Park and its surrounding outstations by the end of the war. Turing also undertook, single-handedly at first, a twenty month struggle to crack the especially secure form of Enigma that the North Atlantic U-boats relied upon. He and his group first broke into the messages between the submarines and their bases during June 1941, the very month when Winston Churchill’s advisors were warning him that the wholesale sinkings in the North Atlantic would soon tip Britain into defeat by starvation. Churchill, Britain’s wartime leader, later confessed: ‘The only thing that ever really frightened me during the war was the U-boat peril‘. Turing’s work had at last made it possible to defuse that peril. The U-boats’ messages revealed their positions, and so the merchant convoys could simply be rerouted away from the submarines—a simple but utterly effective measure.

Turingery—the third of Turing’s three great contributions to the war, alongside the bombe and the breaking of U-boat Enigma—was Bletchley Park’s first systematic method for cracking the coded messages generated by the Germans’ Tunny cipher machine. Tunny, Enigma’s high-tech successor, was Hitler’s BlackBerry. It was used for the highest level traffic. Building on work done by another solitary and taciturn Bletchley Park genius, Bill Tutte, Turing hacked into the Tunny system. Using Turingery, Bletchley Park was able to read the lengthy typed exchanges between Berlin and the generals commanding the armies at the battlefronts, conversations that laid German strategy bare.

The Turingery-inspired code-cracking algorithms that ran on Bletchley Park’s anti-Tunny ‘Colossus’ computers, together with Turing’s anti-Enigma bombes, supplied the Allies with an unprecedented inside view of the enemy’s military thinking. In particular, Bletchley Park had an unrivalled window on German counter-preparations for the looming D-Day invasion of France, which in June 1944 was launched from the beaches of Normandy. If Turing had not broken U-boat Enigma, this invasion of mainland Europe, ushering in the final stage of the war, could have been delayed by months, even years. This was because the gigantic build-up of the necessary troops and munitions, in the southern English ports facing France, could not even have begun while the Atlantic sinkings continued unabated. Without a break into the submarines’ messages, the invasion would have had to have waited until the Allied navies had hunted down the U-boats by conventional means.

Any delay would have been strongly in Hitler’s favour, since it would have given him more time to prepare for the coming attack from across the Channel—more time to transfer troops and tanks from the Eastern front to France, and more time to fortify the French coast and the river Rhine, the most crucial of the natural barriers lying between the invasion beaches and the German heartland. Also, more V1 drones and more rocket-propelled V2 missiles would have rolled off the production lines, to rain down on southern England and wreak havoc at the ports and airfields needed to support the invading troops.

History records that the allied armies took roughly a year to fight their way from the beaches to Berlin. In a counterfactual scenario, in which Hitler had had more time to consolidate his preparations, this struggle might have taken much longer—twice as long maybe. That translates into a very large number of lives. At a conservative estimate, each year of fighting in Europe brought on average about seven million deaths. Returning to the atom bomb example, and to the difficulties of counterfactual history, the killing might still have ended in May 1945, even in a scenario that saw Tunny and U-boat Enigma remaining unbroken throughout the war. Nevertheless, these colossal numbers of lives—7 million had the war had continued for another year, 21 million if, owing to the Atlantic U-boats and a strengthened Fortress Europe, the war had toiled on for as long as another three years—do most certainly convey a sense of the magnitude of Turing’s contribution.

Questions for Discussion (updated):

1. What might life in Britain have been like today if Operation Sea Lion had been successful?

2. Is breaking coded messages in peace time moral?

3. Where does Turing rank in comparison with other major heroes of the second world war such as Churchill, Eisenhower, and Montgomery?

4. What other individuals made personal contributions that changed the course of World War II?

5. What, in your view, are the three most significant individuals who shaped world history?

6. Is there an area of research today that might ultimately become as significant as Turing’s codebreaking work?