 | From our archives...January 1944 : The Scene in the New YearThe turn of the year found the combatants facing serious manpower shortages. The British planners, now concentrating on the D-day landings only five months away, had to face that the manpower was simply not available to ensure that casualties in the forces landed in Normandy could be replaced. Despite their image of overwhelming mass, the Russian army was forced to rely more and more on superiority in armour and guns than on massed manpower. This is no longer available due to the huge losses in previous battles, on the demands of their arms industry in full flood, and on the need for manpower to restore the ravaged lands they have recaptured that had been left devastated by the retreating Germans. The German forces were much depleted with all but the most elite units from now on always well below complement. Their industrial output was being maintained at record outputs by the use of slave labour, but emergency call-ups for their armies could only produce the very young and the unfit. Only the United States could look forward to deploying 1.6 million servicemen now ready for action in Europe, with 1.8 million more in action against the Japanese. In Russia the customary pause in operations was not forthcoming as the Russians demonstrated their newfound skills at mobile warfare as they launched offensive after offensive in the south, the location and timing repeatedly deceiving the Germans. In early January the British press was full of banner headlines saluting the Russians as they surged towards the pre-war Polish frontier and on 6th January crossing it at Rokitno. In the north the Russians finally ended the 880 day siege of Leningrad and cleared the route of the Leningrad-Moscow railway on 27th January, though this offensive was more like the old fashioned Russian sledge-hammer than the rapier thrusts that they were using down south. The British government did not rejoice in quite the same way as the British population at large at these Russian successes for they knew from reading the ‘Purple’ messages of the Japanese Ambassador that Hitler had told him that he was now conducting the war in Russia on the basis of not jeopardising the defence of Western Europe; Hitler had said he had been obliged to reinforce his armies in Italy and the Balkans by 35 German divisions at the expense of the Eastern front. The Deception War. If it is the Russians who have shown unexpected skills in their winter campaign at deceiving the enemy about where the next blow was to fall, it is the old masters, the British, who are now preparing to demonstrate the art on a huge scale. For some months the British deception experts, now joined by Americans, have sought to give the impression that the D-day landings are coming in the Pas de Calais. The creation of the purely imaginary vast military formation, the First US Army Group notionally based in Kent, is already well under way. Now, as a taster for what is to come in Northern Europe, the British in the Mediterranean try to fool the Germans into believing the expected landings in Italy are to come North of Rome, instead of south of Rome in the Bay of Anzio. The deception team in the Mediterranean (A-Force) has now had much experience from the Desert fighting onwards. They put over a story, to cover the preparations for the landing at Anzio, that a pincer attack is being mounted by General Patton’s US Seventh Army against Northern Italy from Pisa on the west coast and Rimini on the east. Advantage is taken of the fortuitous passage of a large fleet of three battleships and an aircraft carrier through the Mediterranean on the way to the Far East to add to the threat. Though the Germans are certainly totally deceived into believing that there is no threat of a landing south of Rome, there is no evidence that Kesselring believed the cover plan either, because his reconnaissance aircraft are successfully prevented from over-flying both the actual preparations for the expeditionary force and the dummy forces. However, Hitler did believe there was a major threat to the Balkans, a belief that was constantly reinforced by the Allied deception campaign, and this continued for many months. It was the reading of the Abwehr signals by BP that enabled the deception teams to build on the enemy’s mistaken fears, and to know when the false stories that they are propagating are being believed. Anzio Landings and the Fighting for Monte Cassino. In the early hours of 22nd January VI Corps of General Clark’s Fifth Army lands at Anzio virtually totally unopposed. General Kesselring has ordered a general invasion alert for the three nights before the landings, but he stands his troops down on the night of the 22nd. He has been told by Admiral Canaris, the head of the Abwehr who happens to be visiting at the time, that there is no fear of a landing in the near future as all the Allied reserves have been drawn into the fighting round Cassino. Unfortunately the leader of VI Corps, the US General John Lucas, backed by Clark, chooses not to take advantage of the lack of enemy troops in the area to strike fast inland, as had been planned, to cut the communications to the Germans fighting round Monte Cassino. He wants to build up his artillery and armour before moving far from the beaches, but lacks the shipping to do this quickly. By the end of the month he has 70,000 troops and 356 tanks ashore, but by then it is too late. The Germans have reacted fast, drawing reserves into the area from both France and the Balkans. Churchill, with all the painful experience of Gallipoli behind him is incandescent, commenting ‘we were hurling a wild cat on the shore, but all we got was a beached whale’. When he learnt that 18,000 vehicles have been landed he asks how many men are looking after them ‘We must have a great superiority of chauffeurs in the area?’. Instead of unhinging the Gustav line, the beachhead becomes an embarrassment because of the difficulties and dangers of resupply, causing the Allies to continue the assault round Monte Cassino in order to try to break through to relieve the beachhead some 60 miles away, when the sensible course would have been to delay until the spring when better weather would enable the Allies to take advantage of their superiority in the air. Before the landings General Clark has mounted attacks on 20th January across the Garigliano south of Cassino. A bridgehead is established at great cost, with the US 36th division being decimated in what they considered had been a suicidal attack thrust on them by Clark. The French to the north of Cassino have made better progress in penetrating through the Gothic line but have had to pause to regroup. But at least the sacrifice in these attacks has drawn the German reserves into the line and away from the Anzio area. General Clark fails to recognise the superior strategy of General Juin, ordering him and his French troops to turn their intended deep outflanking manoeuvre towards Atina into a short left hook into the mountains close round behind Monte Cassino. These attacks on the 25/26th January are pursued with remarkable heroism, but when the Germans counter-attack in the following days they drive the exhausted French back, recapturing many of the mountain peaks. Two thirds of the men of the French assaulting companies have been killed or wounded but the honour of the fighting French is re-established, though the German hold on Monte Cassino remains. The excellent Intelligence that the Allies enjoy throughout this period has been of little benefit in the hostile conditions. In particular the daily reports in the Bullfinch Enigma key of the German 10th Army, first broken on 15th December, gives a full account of the German plans for counter-attacks at Cassino and shows that they are having to commit a large part of their reserves. The one sensible strategic move to avoid a frontal attack on the formidable mountain has been thrown away by incompetent top leadership; at this time General Clark did not seem to value his Ultra intelligence [though he was soon to change his mind when he receives warning from BP of Kesselring’s plans for a major German attack on the beachhead]. Intelligence on the Russian Offensives. The Russians were still providing their Allies with little direct information. However the British were obtaining considerable information on the Eastern front from decrypts of both Enigma and Fish messages, but mostly confined to Luftwaffe sources on the northern part of the front. The decrypts of the messages sent (in the Grampus Enigma key used by the naval forces in the Black Sea area?) by the naval liaison staff to the German armies on the southern part of the front were particularly valuable. They disclosed that the Russians had regained in a few days fighting virtually all the land they had lost to von Manstein’s recent counter-attacks. Whitehall knew that the Luftwaffe had thrown two thirds of their total strength on the Eastern front into these counter-attacks, but had proved largely ineffective because so many of their fighters had been withdrawn to Germany. On 20th January the Joint Intelligence Committee estimated that there were 4 million Germans on the Russian front in some 209 divisions, though many of these much reduced in strength and equipment, if not as yet in morale. (By comparison the Allies were tying down 25 German divisions in Italy, 18 south of Rome). They knew the Germans had virtually no reserves in Russia, and faced some 7-8½ million Soviet men, high in morale and steadily improving in fighting value. They estimated the Soviets had 5,000 mainly modern operational aircraft. A Problem with Enigma: The Introduction of Umkehrwalze D. On 1st January 1944 the Germans made a physical change to the Luftwaffe Enigma machine, the first they had made since they increased the number of different code-wheels to five in 1938. (The German navy had introduced three additional wheels in 1939, brought into service the 4-wheel Enigma machine in February 1942, and then added an alternative variable reflector in July 1943). Despite their recognition that some of the code-wheels had been captured on various occasions, so they must have presumed that the wiring of their five wheels was known to the Allies, the Luftwaffe and Army had never introduced more wheels with different wiring. Now the new reflector was introduced on the Luftwaffe Red key, the principal Luftwaffe key and the most widely broken of all keys by BP. The cryptographers in Hut 6 solved the wiring on that very first day of its use. But ten days later they found a different reflector was in use and it soon became apparent that the wiring of the new reflector, Umkehrwalze D or Uncle Dick to the inmates of Hut 6, was being changed every ten days or so, and that it was completely rewirable in the field. (Well, almost completely; letters J and Y could not be rewired). Now the Hut 6 cryptographers had to use hand methods to solve the stecker plugging and UKD reflector wiring taken together. This might have created a very considerable problem for BP, but the Germans blundered in the way they introduced and used it. Though the Germans distributed a large number of UKDs, they introduced it only slowly to keys other than the Red, and continued to use the standard reflector alongside the new variable one, usually restricting UKD to the most important messages. But they kept the other daily settings the same for both reflectors thus making the solving of the reflector wiring comparatively easy – provided Hut 6 had a crib of about 80 letters. BP put in hand the building of a huge bombe, Giant, which consisted essentially of four normal bombes joined together to handle the long crib. [Giant, like the normal bombes, was built at the BTM works at Letchworth but it was never moved from the factory and was operated there, presumably because it was so difficult to move as it employed a single drive-shaft!] The Americans were developing a machine called Duenna to tackle the problem but it would be many months before these machines could enter service. So until machinery could be introduced, the threat that UKD would become widely used caused Hut 6 to plan emergency measures, such as increasing the staff numbers in Hut 6 and training up 400 juniors (largely Wrens working on the bombes at Stanmore) to attack it using hand methods. [In practice UKD was only ever used by the German Army on one key, Greenshank]. The breaking of Luftwaffe keys hardly faltered; in January over 100,000 Enigma Luftwaffe and Army signals were intercepted by the Y stations, a new high. Keys covering just over 50% of these were broken; 62% of the Air traffic was read and 30% of the Army, on average 1,700 Luftwaffe and 300 Army decrypts per day. Of course many of these contained ‘love and kisses’ but the rest provided a formidable insight into the planning, state of supplies, morale, and activities of the German forces. On 20th January the Chiefs of Staff tell the P.M. that BP is ‘our most important source of Intelligence during the war’. A problem with Fish: The Introduction of the P5 Limitation. During December 1943 the dreaded ‘P5 limitation’ started to appear again on the Fish intercepts. It was first used for a short time on the Herring link to North Africa towards the end of the fighting there in the spring of 1943 but was soon abandoned. Now it reappears on nearly all the Fish links. It was a cunning autoclave system that made the motor wheel stepping dependent in a simple way on the plain text. This resulted in the total loss of depths, so the Testery could no longer find the start positions on all the code-wheels by hand. Luckily there were two of the new Robinsons now working in the Newmanry and a third arrives this month, so the Newmanry can use them to find the start positions of the five ‘chi’ code-wheels. In a remarkable feat, they now use their ‘comparatively primitive equipment of the time’ also to find the teeth patterns on these wheels for the important Bream link to Rome, leaving the Testery to deal with the other wheels, helped by knowledge about the five that the Newmanry have tackled. In his report for the 18th January Max Newman gives the Director the good news that ‘Colossus arrives today’. Can you help?'There is no doubt that the new reflector for the Enigma machine was changeable in that the wiring could be easily altered in the field. Accounts describe it as wireable. But was it possible to chance the wiring by plugs, on the lines of the stecker board? It is known that there was a reflector that was in some sense plugable?'. The Bletchley Park Trust welcomes the preparation of these notes, but the authors are responsible for the statements and the views expressed. |
