page_title: Tallboy (bomb)
section_title: December 1944 – April 1945
hierarchical_section_title: Tallboy (bomb) / Tallboy operations / December 1944 – April 1945
caption_attribution_description: English: Germany Under Allied Occupation A British soldier from 224 Field Company, Royal Engineers, examines a hole made by a 12,000 lb bomb in the 11 foot thick concrete roof of the German U-Boat pens at Hamburg.
context_page_description: Tallboy or Bomb, Medium Capacity, 12,000 lb was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and used by the Royal Air Force during the Second World War.
  At 5 long tons, it could only be carried by a modified model of the Avro Lancaster heavy bomber. It proved to be effective against large, fortified structures against which conventional bombing had proved ineffective.
context_section_description: Bombing of U-boat pens, December 1944 – April 1945
  15 December 1944 – IJmuiden on the Dutch coast,
  617 Squadron attacked U-boat pens with Tallboys. A smoke-screen hindered the bombing, and the results went unseen.
  12 January 1945 – Bergen
  32 Lancasters and one Mosquito of Nos 9 and 617 Squadrons attacked U-boat pens and shipping in Bergen harbour. Three Lancasters of 617 Squadron and one from 9 Squadron were lost; the Germans told the local people that 11 bombers had been shot down. A local report said that three Tallboys penetrated the 3½-metre-thick roof of the pens and caused severe damage to workshops, offices and stores inside".
  3 February 1945 – IJmuiden & Poortershaven
  36 Lancasters of No 5 Group attacked U-boat pens at IJmuiden (9 Squadron) and Poortershaven (617 Squadron) with Tallboys. Hits were claimed on both targets without loss.
  9 April 1945 – Hamburg
  617 Squadron attacked with Tallboys and Grand Slams. Some of the bombs hit their target and no aircraft were lost.
  18 April 1945  – Heligoland
  969 aircraft: 617 Lancasters, 332 Halifaxes and 20 Mosquitos of all groups bombed the naval base, airfield and town "almost into crater-pitted moonscapes". Three Halifaxes were lost; the islands were evacuated the following night.
  19 April 1945 – Heligoland
  36 Lancasters used Tallboy bombs against coastal positions.
  8 December, 11 December 1944
  Urft Dam, (30 mi (48 km) south west of Cologne) was attacked to prevent it being used to flood the area as American troops advanced. The lip of the dam was damaged, but the Germans prevented further damage by lowering the water level.
  21 December 1944 – Politz
  617 Squadron.
  14 March 1945 – Bielefeld and Arnsberg viaducts
  The viaducts were attacked by 617 and 9 squadrons with Tallboys and the first Grand Slams. The Arnsberg viaduct withstood the attack but 100 m (330 ft) of the Bielefeld viaduct collapsed through the 'earthquake effect' of the Grand Slams and Tallboys.
  15 March 1945 – Arnsberg viaduct
  Arnsberg viaduct was attacked again by 9 Squadron. It did not collapse.
  16 April 1945 – pocket battleship Lützow
  Lützow was attacked by 617 Squadron. Despite intense flak, 15 aircraft managed to bomb the target with Tallboys or with 1,000 lb (450 kg) bombs. One near miss with a Tallboy tore a large hole in the bottom of the Lützow and she settled to the bottom in shallow water. One Lancaster was shot down, the Squadron's last loss of the war. The bomb remained sunk near Świnoujście in the middle of main shipping Piast Canal for 74 years, unearthed during the preparatory works for deepening of the Świnoujście-Szczecin fairway in September 2019.
  25 April 1945 – Berghof
  Hitler's vacation home, the Berghof, near Berchtesgaden was attacked with a mixed force that included six Lancasters of 617 Squadron dropping their last Tallboys. The bombing appeared to be accurate and effective.
caption: The 11-foot thick concrete roof of submarine bunker "Fink II" in Hamburg, after having been penetrated by a Tallboy in early April 1945
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