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The final months of World War Two saw a coordinated Allied invasion of Germany. By early 1945, the balance of power favoured the Allied forces in Europe. On the Western Front the Battle of the Bulge – the last major German offensive of the war – had ended with the Germans pushed back to their starting points along the Siegfried Line, a defensive line along the Western German border. This failure exhausted Germany’s strategic reserve, leaving it ill-prepared to resist the final Allied campaigns in Europe. On the Eastern Front, the Soviet Red Army were advancing through Poland and East Prussia towards Berlin. These rapid advances destroyed German combat units and severely limited Hitler’s ability to reinforce his Western defences. With the Western Allies making final preparations for a powerful offensive into the German heartland, victory seemed increasingly likely.


This album was first published on 16 March 2020.

‘Whiting’ was a Tunny radio link between Golssen, near Berlin, and Heeresgruppe Kurland (Army Group Courland). In October 1944, 30 divisions of Heeresgruppe Kurland were encircled and trapped in Latvia, in what the Germans referred to as ‘Fortress Kurland’. Dated 14 February 1945, this intercepted Lorenz message reports on the layout of field artillery assets in that area. Heeresgruppe Kurland remained isolated until the end of the war.

Operation Plunder was an Allied military operation to cross the Rhine near Wesel. It began on the night of 23 March 1945. A floating pontoon bridge was in place there by 4pm the following day. The operation was part of several coordinated Rhine crossings. The United States Army had already unexpectedly captured the Ludendorff Bridge at Remagen, enabling 25,000 troops to cross the river there. They also crossed the Rhine near Oppenheim on 22 March and Boppard two days later. With the German defences all along the Rhine falling apart, the industrial Ruhr region was enveloped depriving Germany of its war manufacturing capabilities.

BMP reports (named after Arthur Bonsall, Philip Moyes and Frederick Prior) provided signals intelligence to Allied Air Force commanders based on analysis of enemy fighter reactions. ‘Window’ refers to clouds of aluminium foil strips used as a radar-confusing technique by the Royal Air Force. The clouds would look like Allied aircraft formations to the Germans. This extract from the BMP night report of 23/24 March 1945 refers to the Allied bombing of the area around Wesel as preparation for Operation Plunder.

Introduced in October 1944, the SG-41 was the last cipher machine developed by Germany during World War Two. It used pin-wheels, rather than rotors, in its encryption mechanism and was intended to supersede Enigma. While Enigma’s rotors always advanced one position forward for each letter enciphered, the SG-41’s pin-wheels interacted with each other and moved irregularly, both forwards and backwards. The letter ‘J’ is marked in red on the machine’s keyboard, probably as it is used to shift between letters and numbers. Only a handful of SG-41 messages were readable by the Codebreakers at Bletchley Park, because they were ‘in depth’ (enciphered at the same position). Otherwise, even when pure key was available, the wheel settings and pin patterns could not be reconstructed.

The Brown Story was a daily diary of activity on the Brown Enigma network. Each message or piece of operator chatter was listed and paraphrased. Brown Enigma operators were unusually indiscreet in their use of language. A report produced at Chatham Y Station noted ‘Operators appear to enjoy a freedom from wireless discipline which is not shared by any other group’. This report from April/May 1945, jokily entitled ‘Happy Events in the Brown Family’ and listing a record of ‘Births, marriages & deaths other notable fun events’, reveals Bletchley Park staff taking enjoyment in seeing the network collapse as the end of the war approached.

As the Western Allies continued their advance, the German High Command in Berlin, under siege by the Soviet Red Army, refused to send reinforcements to the west. Outgunned by the weapons and resources available to the Allies, and sustaining heavy losses, the German troops felt increasingly helpless. This message, from April 1945, refers to the situation for German troops being ‘strained to the utmost’.

Interception and analysis of transmissions at Bletchley Park from the German air defence network allowed British and American bomber routes and tactics to be refined and helped to minimise losses. They also revealed the heavy losses suffered by Germany as the Allied forces continued to gain territory. This German Air Traffic Report, dated 26 April 1945, refers to the capture of Bremen by British 3rd Infantry Division under Major-General Whistler.

Lorenz messages were decrypted in the Testery, using Tunny machines. This is one of few surviving pages from a message dated 30 April 1945 which has been deciphered into German. Tunny was the nickname given by Bletchley Park cryptanalysts to message traffic sent by German Lorenz cipher machines. This decrypt reports, “Enemy attacks supported by armour against our defence front captured Bad Elster, Sohl, Raun and Bad Brambach”.

The text on the second page of the Lorenz decrypt of 30 April is still recognisably German but contains many unresolved characters. These sequences, indicating a figure or letter shift, were preserved because they provided patterns the cryptanalysts could exploit. The text reveals increasing advances by the Western Allies into German territory, referring to “Increasing enemy pressure in area N and W of Baernau” and “Enemy attack against Paulusbrunn”.

After the Western Allies crossed the Rhine, German armies in the west began to fall apart. The Allies started a general advance across Germany, with the Americans pushing in the centre and the British advancing in the north. The Germans sought to make a final stand at the city of Hamburg. British troops were met with fierce fighting inside the city – the last significant remaining pocket of resistance in the north. Hamburg was ultimately surrendered to the Allies on 3 May 1945.

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