Bielefeld, 14 March By mid-March 1945, over had been dropped on the
Bielefeld viaduct in 54 attacks and damage from 17 hits in one raid was repaired in 24 hours. After an abortive attempt against viaducts at Arnsberg and Bielefeld on 9 March the bombers returned on 13 March, when 9 Squadron and 617 Squadron sent 19 Lancasters each against the same targets, two of the 617 Squadron aircraft carrying Grand Slams, escorted by 75
Mustang Mk IIIs (P-51Cs) from 11 Group. The attack at Arnsberg by 9 Squadron was called off after two aircraft bombed and 617 Squadron turned back from Bielefeld after 129 Squadron (Mustang Mk IIIs) reported unbroken cloud all the way to the target. On 14 March, fifteen Lancasters of 617 Squadron, carrying 14 Tallboys and a Grand Slam, all fuzed for 11 seconds' delay, tried again as fifteen 9 Squadron Lancasters made another attempt against the railway viaduct at Arnsberg. The weather was clear to the targets with some cloud around Bielefeld and a haze over both targets. Escorts from 11 Group consisted of 74 Mustang Mk IIIs and
8 (Pathfinder Force) Group provided four
Oboe Mosquitos each from 105 and 109 squadrons to mark the targets. A Mosquito of
627 Squadron was present to film the attack. The Lancasters of 617 Squadron flew around Bremen then found that there was cloud on the north side of Bielefeld forcing PD112
S with the Grand Slam to attack from the south after resetting the SABS, followed by the photographic Mosquito. One of the 105 Squadron Oboe Mosquitoes dropped four Target Indicator bombs which landed about to the south-south-west of the target. At and from , a far from ideal height, the Grand Slam fell from PD112
S, which jumped higher at the loss of weight. After 35 seconds, the bomb hit the ground about short and exploded the site erupting as the Tallboys came down. The pilot of the photographic aircraft, which recorded the attack from shouted "You've done it!". The effect of the Grand Slam could not be distinguished from that of the eleven Tallboys but photographic reconnaissance by a Spitfire from 542 Squadron, following the bombers, then a Mosquito from 540 squadron later on, showed that of the north viaduct and of the south viaduct had been demolished, depositing about of rubble into the valley.
Arnsberg, 15 March On 15 March, in a haze with some cloud over the target, two aircraft of 617 Squadron with Grand Slams fuzed for 11 seconds' delay and 14 Lancasters of
9 Squadron, carrying Tallboys, attacked the railway viaduct at
Arnsberg again. A close fighter escort of 34 Mustang Mk IIIs was provided by 11 Group. A photographic Mosquito, KB433, was laid on by 627 Squadron and another 141 fighters were in the vicinity covering raids by 4, 6 and 8 Groups. The long viaduct, built from brick and stone faced with concrete, crossed the Ruhr in five spans. In poor visibility the crew of the photographic Mosquito saw that "the whole force made one run into sun and one bomb seen to drop". This was the first Grand Slam, dropped from at The photographic crew reported, "Second run into sun and one or two bombs fell. Individual runs then made. No direct hits seen. Majority of bombs fell to the east....". The second Grand Slam was brought home after several bomb runs because of the haze and the Lancaster, PB996, landed at the emergency bomber landing ground at
RAF Manston. Ten Tallboys were also dropped with no effect and no aircraft were lost. On the return journey the port inner propeller of NG384 over-speeded and could not be feathered and then oil leaking out from behind the propeller caught fire and the pilot, Flight-Lieutenant F. A. Jones ordered the crew to abandon the aircraft south of the target. Four of the crew parachuted but then the fire went out and Jones force-landed at
Gosselies near Charleroi.
Arnsberg, 19 March On 19 March, 19 Lancasters of 617 Squadron, six with Grand Slams and 13 with Tallboys, attacked the viaduct again as 9 Squadron attacked the Vlotho rail bridge, in fairly cloudy weather at high altitude, with thin patches lower down. The bombers were escorted by 88 Mustang IIIs from 11 Group. PD329
Y, a Lancaster without bombs from 463 Squadron carried two cameramen from the
RAF Film Unit accompanied 617 Squadron. A report from
129 Squadron, part of the escorting Mustang force, called the bomber formation tight but then the bombers flew into cloud at . The squadron flew over the Möhne Dam with its barrage balloons, smoke screen and anti-aircraft fire. The cameramen in PD329
Y had been briefed to film PB966
C, flown by Flight-Lieutenant P. H. Martin and formated on its starboard side, with a cameraman in the nose turret to film the Grand Slam as it fell away and the other on the floor of the fuselage filming vertically. Closer to the target, PD329
Y dropped back and flew on the port quarter of PB966
C.The bomb was not to be dropped from under but Martin, the pilot, could not coax the bomber above . On its five-minute bombing run, Martin had to fly within the tolerances of its SABS bombsight, within of airspeed and +/- of altitude. The cameramen started filming and when the bomb dropped, PB966
C jumped higher. The bomb began its spin and came down on the western span, which disintegrated, along with the roofs of buildings nearby. All but one Lancaster of the first wave, whose Tallboy hung up, bombed. A second wave bombed fairly accurately but one Grand Slam fell off line due to a SABS fault. Two spans of the bridge, about long and one pier had been destroyed, the track on the west bank had been cut, of one of the embankments had been shoved out of line and the entrance to a tunnel on the east bank had been blocked; no damage had been caused to a
Red Cross camp nearby. After the war the casings of a Grand Slam and a Tallboy were found at the site; the Grand Slam was thought to have landed flat on a road and only the explosive at the rear of the casing detonated; the Tallboy hit a wall, broke up and buried itself in the ground without going off.
Arbergen, 21 March Twenty Lancasters of 617 Squadron, two carrying Grand Slams and the rest Tallboys, flew in good weather with little cloud to
Bremen to attack the double-tracked railway bridge at Arbergen which crossed the
Weser near
Nienburg. The bridge was long with three steel girder spans. The railway approached the river from the south-west along an embankment until from the river where it crossed a meadow on a low-lying steel viaduct resting on piers. The bombers were escorted by twenty Mustang Mk IIIs of
306 (Polish) Squadron and
309 (Polish) Squadron. Another five fighter squadrons were provided to escort a day raid by 1 and 8 Groups on an oil refinery at Bremen; other Main Force aircraft attacked targets in
Münster and
Rheine. The first Grand Slam was dropped from , landing short and the second fell off target to the north, due to flak (anti-aircraft fire) and aiming problems. The Tallboys hit the middle of the bridge and the ends were blown off their piers; the pier to the east collapsed onto the ground and the western pier was twisted and sagged to the ground at one place; part of the railway track, above the embankment and the first pier on the west side, was wrecked. One Lancaster was shot down near Okel and left a crater deep; five Lancasters were damaged by flak and an attack by a Me 262 jet fighter.
Nienburg, 22 March Twenty Lancasters of 617 Squadron, six carrying Grand Slams fuzed for 25–30 seconds' delay and 14 with Tallboys with 25–35 seconds' or one-hour delay, attacked the railway bridge at Nienburg, between Bremen and
Hanover, in atmospheric conditions ideal for bombing. A railway bridge at Bremen was attacked at the same time by 9 Squadron with Tallboys. The bombers were escorted by 114 Mustang Mk IIIs and 69 Spitfire Mk IXs from 11 Group squadrons. The Lancasters of 617 Squadron bombed within one minute, dropping five Grand Slams and twelve Tallboys. One Lancaster crew claimed a near miss with a Grand Slam and another crew claimed a hit, It had been planned that the fourth and eight rows of Lancasters would not bomb on the first pass and Flight Lieutenant L. S. Goodman reported that on the second bomb run the bridge was under water, the spans having been broken or blown off their piers. A third Lancaster crew found that their bomb would not drop, despite two attempts and the bridge collapsed before the third try, leaving the crew to take it home. A fourth Grand Slam was reported to have hit the east end of the structure. Reconnaissance photographs showed that the bridge had been destroyed.
Bremen, 23 March Another railway Bridge near Bremen was attacked later in the day by twenty 617 Squadron Lancasters, six carrying Grand Slams and 14 with Tallboys. The bridge at Bad Oeynhausen was attacked by 9 Squadron. The weather was clear and ideal for bombing but was also good for the Bremen anti-aircraft defences. The bombers were escorted by 41 Mustang Mk IIIs from 11 Group with seven more squadrons in the vicinity. A total of 128 Lancasters took part in the bombing from 1 Group and 5 Group, most accompanying 617 Squadron on the attack on the bridge at Bremen. The Germans started to generate a smoke screen but were too late; two hits were observed before the smoke screen and wreckage blocked the view. The pitch control on one of Lancaster PB996's engines made the aircraft lose speed and its bomb was dropped on a jettison area; the pilot of PD112 decided to bomb despite the bomb-aimers clear vision panel being smashed by flak. Three hits were claimed and one Tallboy hung up when the bomb aimer tried to drop it then fell off 15 seconds later, overshooting the bridge. Later analysis found that a Tallboy had landed on the bank at the south end of the bridge about from the abutment and the shock of the explosion shifted it, making the span fall into the river. A Tallboy hit the north end of the bridge, the damage being swiftly repaired; another to the south which was filled in and new track laid. Eventually the Germans demolished the bridge to create an obstacle to the Allied ground advance. Lancaster NG489 was hit by flak and the crew jettisoned the Grand Slam to regain control. Several other Lancasters were hit by anti-aircraft fire and four others were attacked by Me 262s, fifteen of which were seen on the flight to the target.
Farge, 27 March Twenty Lancasters of 617 Squadron, 13 carrying Grand Slams, the remainder carrying Tallboys, attacked the
Valentin submarine pens in clear visibility escorted by 90 Mustang Mk IIIs of 11 Group. Since October 1944, building work had been seen at
Farge, a village on the Weser river, north of
Vegesack and north-west of Bremen. The building had of the structure above ground and below, was long and wide, enclosing of space. The walls and roof were made of reinforced concrete with arched
trusses on the walls, filled with concrete. The roof was about thick and was being reinforced to a thickness of . Farge was intended for the assembly of type
XXI U-boats. The shipyard at Vegesack and the site of the building, was code named , construction beginning early in 1943. The site was chosen because it was on the convex side of a curve in the river less prone to silting; the river bed was dredged to a depth of to allow submarine sections in on barges and assembled U-boats out. Production was expected to begin in March 1945, full production to be achieved in August; the schedule had slipped but production was to start within two months. One Lancaster had returned soon after take-off and another turned back over the target with engine-trouble, ditching the Grand Slam in the North Sea. Moderate to heavy flak was encountered by the gaggle of Lancasters but there was no fighter opposition. The bombs were dropped in about a minute and despite 1-hour delay fuzes, three bombs exploded immediately. Two of the fourteen hits on the pens were by Grand Slams and one by a Tallboy, the hits landing on the un-thickened part of the roof on the west side. The Grand Slams penetrated into the concrete causing about of the roof to fall in bringing down two moveable cranes. The thickened part of the roof and a periscope-testing tower were also damaged. One bomb damaged power stations, concrete mixing facilities and shelters on the north side. Marines who had been inside the building reported later that there was a huge concussive effect, which severely depressed their morale; no aircraft were lost.
Hamburg, 9 April Seventeen Lancasters from 617 Squadron were dispatched to bomb the Finkenwerder
U-boat pens in
Hamburg, two with Grand Slams and the rest with Tallboys. The pens were inside a -building with a roof thick, reinforced by steel beams and trusses. Forty Lancasters from 5 Group were to bomb oil storage tanks nearby. The weather was clear with some haze, a thin layer of cirrus clouds above the city but the visibility was very good. A fighter escort from 11 Group consisted of 120 Mustang Mk III, 30 Mustang Mk IV, 59 Spitfire Mk IX and 24 Spitfire Mk XVI to counter any attempts by Me 262 jets to intervene. fighters, including jets, attempted to intercept the formation and there was much flak, which damaged six Lancasters before they bombed. Buildings to the north and west were hit and a reconnaissance photograph showed seven hits, four penetrating the roof. A post-war report recorded six hits by Tallboys, the two Grand Slams and the other Tallboys landing in the water. The six Tallboys had penetrated the roof part way, hit girders and exploded, blowing holes through the ceiling and depositing hundreds of tons of concrete into the pens. There had been 3,000 people inside the pens, fewer than usual, because it was a Friday, when German workers left at ; 27 people were killed, about sixty were seriously injured and a panic ensued;
U-906 and
U-1192 were damaged. About thirty Me 262s appeared and
467 Squadron RAAF, on the oil tanks raid, accelerated and turned, ending up bumping along behind the 617 Squadron slipstream. The Mustangs jettisoned their drop tanks and 122 Squadron bounced the German jets which raced away. The Polish 306, 309 and 315 squadrons attacked the jets and claimed three Me 262s shot down and three damaged; two Lancasters were shot down.
Heligoland, 19 April The coastal gun batteries on the islands of
Heligoland and
Düne in the
Heligoland Bight, the south-eastern extremity of the North Sea, were attacked on 19 April. The military installations on the main island comprised a radar installation covering the
Elbe and Weser rivers, an airfield and a coastal battery each with and guns. To ensure that Allied ships could enter the Elbe and Weser estuaries, Bomber Command intended to attack the island with bombs but at least forty heavy anti-aircraft guns on the islands had to be silenced. The gun positions had a diameter of about and only hits or near misses would be effective. On 18 April, 969 bombers had attacked the anti-aircraft guns but some remained operational. On 19 April, 20 Lancasters of 617 Squadron attacked with six Grand Slams and fourteen Tallboys; 16 Lancasters from 9 Squadron carried Tallboys fuzed for 25 seconds' delay. A Mosquito from the RAF Film Unit accompanied the raiders and a fighter escort was provided by 11 Group and
12 Group, consisting of 11 Mustang , 42 Spitfire Mk IXs and 26 Spitfire XVIs. The gun emplacements were at the north and south ends of the island and three aiming points were chosen, two for 9 Squadron and one for 617 Squadron. Thin stratocumulus cloud was encountered from and six of the 9 Squadron bombers were to act as wind finders, the results being broadcast to the rest of the squadron at H minus 5. As 9 Squadron flew towards the island, they were surprised to see 617 Squadron attacking, climbed to keep out of the way and circled while waiting for their fighter escort. The attack by 617 Squadron was made in two waves against hardly any anti-aircraft fire and all bar one aircraft bombed. Photographic evidence showed two hits on aiming point H and several near misses, which added to the damage. Another attack by the Main Force was planned but the war ended before it took place. ==Aftermath==