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 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, ( 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 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 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. One of the bombs 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. Operations to defuse and remove it were undertaken in October 2020. It exploded