World War Two: The Enigma Codebreakers Part 2

Throughout the second world war, the Nazis believed that their Enigma coding machine was unbreakable, but the British had uncovered it's secrets. This ultimately shortened the war by an estimated 3 years and by the 8th May 1945, when the Allied leaders were celebrating victory in Europe, the jubilant public were completely unaware of the vital role the code breakers of Bletchley Park had played in the downfall of Hitler and Nazi Germany.

ULTRA's significant role

By 1945, it would have been easier for Himmler and Goerring to ring Bletchley Park for Hitler's orders rather than wait for them to be decyphered by their own headquarters.

During the Battle of Britain in the summer of 1940, Bletchley park broke into 2 keys used by the Luftwaffe and ULTRA gave a clear picture of the German Air Force's order of battle and the overall strategy of it's commander Hermann Goerring.

This allowed R.A.F Fighter Command to preserve the narrow margin which gave it ultimate victory. In an earlier example in June 1940, Bletchley ptovided the Admiralty with a warning about the vulnerability of German warchips to the aircraft carrier H.M.S. Glorious which was then withdrawing from Norway.

Glorious was under threat, but the codebreaking at Bletchley park had still been in it's infancy and the Navy ignored the warning. On the 8th june 1940, Glorious was intercepted and sunk by the German battle cruisers Scharnhorst and Gneisenau.

The loss of Glorious brought home to the Navy just how important ULTRA information could be. ULTRA came into prominence again in 1942 during the campaign against Rommel's Afrika Korps in the western desert.

The distance of the North African desert theatre from Germany threw up mass volumes of Enigma traffic and breaks into the Luftwaffe cyphers and the more stubborn German Army cyphers gave British commanders a clear picture of rommel's order of battle, capabilities and shortages which plagued the Afrika Korps.

However, the knowledge did not prevent the loss of Tobruk and 8th Army's retreat to El Alamein, but in July of 1942 it played a vital role in halting the Afrika Korps' advance.

The then commander of the 8th army General Auchinleck later stated that " But for ULTRA, Rommel would have got through to Cairo". ULTRA information also enabled British aircraft to wage a devastating war on the Mediterranean convoys supplying Rommel.

In October 1942, just before the second battle of El Alamein, they sank nearly 50% of German cargo, however, the influence of ULTRA on the battle itself in which Auchinleck's successor Montgomery enjoyed a 5 to 1 adavntage in tanks and aircraft, was less important.

Some military historians have argued that so comprehensive was the ULTRA information that was available to Montgomery as Rommel withdrew, that it was a surprise that the Afrika Korps were not finished off before it's retreat ended in Tunisia.

On at least one occasion the delay enabled Montgomery to read a message from Hitler to Rommel before it had even been delivered to the commander of the Afrika Korps.

 U-110 was captured by HM Ships Bulldog, Broadway and Arbretia on May 9, 1941
U-110 was captured by HM Ships Bulldog, Broadway and Arbretia on May 9, 1941

The Battle for the Atlantic

Nowhere was ULTRA more important however than in the battle against the German U-boats in the battle for control of the Atlantic and nowhere was it more vital to conceal the source of the information.

Bletchley Park broke the U-boats Enigma in June 1941, the Atlantic convoys were stretched to their limits and the use of decrypts to lure convoys away from the waiting U-boats dramatically reduced their losses.

Between June and November 1941, the total tonnage lost, fell from 282,000 tonnes to 62,000 tonnes, the difference between Britain's survival and starvation. To achieve this first critical break into the U-boats code, the British were helped by a remarkable incident.

In May 1941, U-110 was put out of action on the surface and she was boarded. On board was located it's Enigma machine and it's daily setting sheets, the boat's captain drowned in a last-ditch attempt to prevent the capture of this vital material. U-110 was sunk and German Naval Intelligence never suspected that she had yeilded up her vital secret.

But in the Autumn of 1942, Bletchley Park was back to square one as the U-boats changed to a new Enigma key known as Shark. This wasn't broken until Dcember and the see-saw battle between the U-boats and the convoy's protectors reached crisis point by March 1943.

By then the forces escorting the convoys at sea and in the air, were finally strong enough to turn the tide conclusively. By the late summer of 1943, the U-boat command had been crippled.

Operation Torch, the Allied invasion of French North Africa
Operation Torch, the Allied invasion of French North Africa
The codebreakers of Bletchley Park
The codebreakers of Bletchley Park
Operation Overlord, D-Day
Operation Overlord, D-Day
Omaha Approach by Dave Harris
Omaha Approach by Dave Harris
The German High Command
The German High Command
German surrender at the Falais gap
German surrender at the Falais gap

Malta and Overlord

In addition to positive operational information, ULTRA could also provide negative information of enemy intentions which was just as vital. In the beginning of November 1943, a vast Allied invasion fleet was assembling for the invasion of French North Africa.

German Naval Intelligence had mistakenly concluded that it was a huge convoy bound for Malta. The codebreakers at Bletchley were monitoring the German's every move, broken Luftwaffe keys provided the information that no reinforcements were being flown into the area.

By now ULTRA had achieved such a wide ranging view of the German order of battle that it was possible to tell that units that could be moved, where not being moved. ULTRA was also of crucial importance in the gathering preparations for the cross channel invasion of Normandy, codenamed Overlord.

It was critical to be aware of the enemy's strength in the planned invasion area, but until the beginning of 1943, the German forces there used landlines rather than Enigma. The Allies had to rely on information from agents, the French Resistance and photo reconnaisance to build up a picture of the German defences.

In early 1944, Bletchley Park broke the new German Army and Luftwaffe cyphers, enabling the planners of the Normandy invasion to identify the divisions in Northwestern France and modify their own plans accordingly.

Bletchley Park had been reading the German High Command's traffic since 1941 and the interception and decrypting of this traffic provided information that the complex Allied deception plans that preceeded the Allied invasion of Normandy had been swallowed hook, line and sinker by the German authorities.

When the Allies landed in Normandy on D-Day (6th June 1944), they had learned much from ULTRA and therefore were certain of the whereabouts of nearly all of the enemy's armoured and mobile divisions.

After D-Day, Allied air power's progressive destruction of landlines insured that more and more Enigma traffic filled the airwaves. On the 10th June, Bletchley was able to pinpoint the exact location of the German headquarters of the Panzer Group West, the enemy's armoured strike force. The same day it was bombarded by Allied aircraft.

With this went all German hopes of splitting the Allied beachheads in a counter-attack. Throughout the battle of Normandy, Bletchley park provided the Allied land commander General Montgomery with detailed knowledge of German strengths on the frontline, the effects of Allied airstrikes and the eventual order from Hitler of the counter-attack at Mortain as the Allies attempted to break out from Brittany.

This intelligence led to the destruction of Army Group B's armoured reserve and to the destruction of two German armies and a Panzer Group in the Falais Gap.

The range and volume of intelligence provided by ULTRA transformed the process of decision making for the Allied military leadership. General Eisenhower, the Supreme Allied Commander in the European theatre, stated that "ULTRA had simplified my task as a commander enormously".

It had saved thousands of British and American lives and in no small way had contributed to the speed in which the Germans were defeated.

Like their HIgh Command, the German troops on the ground remained ignorant of this vital extra dimension available to the enemy. As the war drew to an end and the Soviet Army encircled Hitler's bunker in Berlin, Bletchley Park was still hard at work.

Roosevelt and Churchill meet in Casablanca
Roosevelt and Churchill meet in Casablanca

Hitler's Last Stand

From Hitler's last headquarters where he marshalled phantom armies on the maps in his war room, came the despairing cry "Why do you not do as I have ordered, why do you not answer?"

On the 15th April 1945, the codebreakers read Hitler's last order "Once again Bolshevism will suffer ages old fate, it will founder on the capital of the Rheich, Europe will never be Russian".

At the highest levels, ULTRA greatly eased theproblems of devising Allied strategy, when Roosevelt and Churchill met at Casablanca in January 1943, Churchill had been receiving a steady stream of ULTRA information for 3 years, without it, his and Roosevelt's picture of the war and the decisions which flowed from it would have been radically different.

As the end of the war approached, the Bletchley Park machines began to wind down, the role of it's codebreakers in the war in Europe was at an end. For security reasons, all the equipment at Bletchley was destroyed. Only a handful of wires and components remain of Alan Turing's revolutionary computer. The Colossus machines were broken up and the one at Bletchley Park today is merely a reconstruction.

Geese still waddle around the lake at Bletchley Park, reminding visitors of Churchill's tribute that the codebreakers who presided over his ULTRA secret were the geese that laid the most golden of eggs.

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Comments 2 comments

William F. Torpey profile image

William F. Torpey 5 years ago from South Valley Stream, N.Y.

Truly fascinating history, Dave Harris. I knew, generally, that the British and WW II Allies had broken the German code, but this is the first time I've read a detailed account of it. You've certainly done a thorough job. Great work. Thanks.


Dave Harris profile image

Dave Harris 5 years ago from Cardiff, UK Author

Thanks William, hard to imagine what things might have been like if it hadn't been for those men and women. Thanks for commenting!

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