'Blitz Week' was the US semi-official designation of the most intensive bombing campaign undertaken up to that time by Brigadier General Frederick L. Anderson’s 8^th AAF (24/30 July 1943).

Planned by Major General Ira C. Eaker, an earlier commander of the 8^th AAF, the 'Blitz Week' was part of 'Gomorrah', and launched major raids against Herøya and Trondheim in Norway (24 July), Hamburg, Kiel and Warnemünde (25 July), Hamburg and Hanover (26 July), Kassel and Oschersleben (28 July), Kiel and Warnemünde (29 July), and Kassel (30 July).

The 'Blitz Week' started on 24 July when 324 Boeing B-17 Flying Fortress four-engined heavy bombers were despatched against two targets in Norway from several bases, and all but 15 of them making the rendezvous. There was cloud across the North Sea, but clear skies had been predicted over the target areas. The destination for Brigadier General Frank A. Armstrong’s 1^st Bombardment Wing was Herøya, some 600 miles (965 km) distant, where the Germans had just completed a new nitrate factory. Colonel Curtiss E. LeMay’s 4^th Bombardment Wing had B-17 bombers with additional wing tankage, and was therefore despatched to attack the harbours of Bergen and Trondheim, some 950 miles (1530 km) distant. Both wings crossed the North Sea at 2,500 ft (760 m) for maximum fuel economy, and then climbed to between 16,000 and 20,000 ft (4875 and 6095 m) to bomb. At Herøya 167 B-17 bombers stopped nitrate production for 3.5 months and led the Germans to abandon the nearby but unfinished aluminium and magnesium plants. The German Flak resistance was minimal, and damaged only one aeroplane that limped into a crash-landing in neutral Sweden. The 4^th Wing’s aircraft bombed Trondheim, but Bergen was covered by cloud and this detachment’s aircraft brought their bombs back to England. Apart from Junkers Ju 88 twin-engined heavy fighters sent to find the bombers on their return flights, the German aerial opposition was negligible.

Early in the afternoon of 25 July the bombers lifted off and passed over the town of Cromer on the Norfolk coast of East Anglia, which was a favourite routing point for bombers making for north-western Germany. One combat wing of the 1^st Wing headed to Kiel and the wing’s other elements to Hamburg, and the 4^th Wing flew to an aircraft factory at Warnemünde to the east of Kiel. Only the Kiel force completed its mission, for elsewhere unexpected cloud to search for and attack targets of opportunity. A pall of smoke some 15,000 ft (4570 m) high hung over Hamburg after the previous night’s 'Gomorrah' raid by Air Chief Marshal Sir Arthur Harris’s RAF Bomber Command, and this hindered the sighting of shipyards and a Diesel engine works. As it was, only the first formation was able to bomb before cloud intervened. The day’s price was high, 19 B-17 bombers being lost, of which five were claimed by anti-aircraft fire.

Despite its losses and the damage suffered by many aircraft which did manage to return, the VIII Bomber Command was again able to despatch more than 300 bombers within 24 hours, but heavy overcast disrupted their assembly despite the use of new techniques, and the groups which had been delayed were then recalled. As a result some formations bombed targets of opportunity along the German coast, and the intended targets at Hamburg and Hanover were each attacked by only two combat wings. Even so, the 92 bombers which attacked the Continental Gummi Werke at Hanover, a synthetic rubber plant and major tyre factory, achieved considerable success. Damage resulting from 21 direct hits reduced production by almost 25% for several weeks. The German defences were well prepared, however, and launched concentrated fighter attacks on the leading bomber formations on their way to the target area.

Although fair, the weather forecast for 27 July was not certain enough for a mission, but at dawn on 28 July the VIII Bomber Command launched its most ambitious attack yet in an attempt to destroy German fighter factories. Taking the well established North Sea route, the B-17 bombers of the 1^st Wing planned to press inland to the Fieseler components works at Kassel, while those of the 4^th Wing made the deepest penetration so far into Germany, to an assembly plant at Oschersleben. The 182 aircraft despatched to Kassel encountered cloud, resulting in limited and generally ineffective bombing. Returning to meet their fighter escort above the German/Dutch frontier, one formation was attacked by Messerschmitt Bf 109 single-engined fighters firing rocket projectiles. Each Bf 109 appeared to carry two launcher tubes, one below each wing, and fired its time-fused weapons at a range of about 985 yards (900 m). Although many of the rockets exploded among the B-17 bombers of Colonel Maurice A. Preston’s 379^th Bombardment Group, none made a direct hit but fragments inflicted minor damage on several aircraft. The attack plan called for the bombers to feint toward the area of Hamburg and Kiel area before turning to the south-east in the direction of their real target, but the 120 bombers of the 4^th Wing were soon confronted by adverse weather and became scattered.

Oberleutnant Hans Philipp’s Jagdgeschwader 1 made contact almost at the coast and its Focke-Wulf Fw 190 single-engined fighters scored against the bombers, some of which had strayed towards Denmark. One stricken B-17, crashing into two others, brought all three down. From engagements primarily in the area of Heligoland, 15 of the 4^th Wing’s bombers failed to return. While other formations turned back in some confusion, the aircraft of Colonel Frederick W. Castle’s 94^th Bombardment Group and a few machines of Colonel Archie J. Old’s 96^th Bombardment Group pressed forward into Germany. Castle realised that his group’s chance of making a successful attack depended on finding a break in the clouds below at the right time and place but, after coming so far, he considered this a chance that was worth taking. Even in fine visibility the aircraft factory would have proved difficult to locate for there were no significant features like rivers or mountains as landmarks in the vicinity. However the 94^th Group was lucky, for only a few miles from the target a gap in the undercast allowed the lead bombardier to recognise a crossroads a few miles from his aiming point. Quickly calculating the time from target, he released his bombs by calculation and 14 other bombers also released their loads by this signal, while 13 aircraft of Colonel William B. David’s 388^th Bombardment Group in a following formation were also able to make a successful attack. Photo-reconnaissance on the following day revealed an excellent concentration of bombs on the factory, which lost an estimated month’s production of about 50 Fw 190 fighters.

The 94^th Group returned to Bury St Edmunds without the loss of a single aeroplane in combat, although the German fighter opposition encountered had been large enough to produce a crop of no fewer than 21 German aircraft destroyed. The tempo of operations and the strength of the opposition were by now combining to to tell on men and aircraft, and it was now not possible for the Americans to maintain the same attacking strength. On 29 July the 4^th Wing set off for Warnemünde, the target it had tried to attack four days earlier, and on this occasion half of the wing was able to do excellent bombing, destroying 18 of the 27 buildings at the Heinkel assembly plant engaged in Fw 190 production. The 1^st Wing flew to Kiel and unloaded 767,000 propaganda leaflets and 208 tons of bombs over the shipyards.

At dawn on 30 July both B-17 wings lifted off their British bases to attack Kassel. The sky was clear all the way to the target and accurate bombing was possible. Republic P-47 Thunderbolt escort fighters, flying deeper into Germany than ever before by virtue of the carriage of drop tanks to meet the returning bombers, encountered German fighters in great numbers. The mission had been started by 186 B-17 bombers, and of those which entered German airspace, 12 did not return and a number of others were scrapped after managing to land back in England.

The weather on 31 July was also good, but the German radar screens found no echoes against which to despatch the defending fighters, as the battle-weary B-17 groups were in no position to fly another major mission to Germany without a short period of recuperation to rebuild their effective strengths in men and machines. Thereafter the weather enforced an operational lull during the first days of August.

'Blitz Week' had proved the most intensive period of US bombing operations up to this time. When the first raid had been despatched Norway the 15 B-17 groups had totalled about 330 bombers and crews ready for operations, but 'Blitz Week' had reduced this to fewer than 200 bombers and crews. About 100 B-17 bombers had been lost during operations or scrapped as a result of extensive damage, and the equivalent of some 90 crews (some 1,000 men) were dead, wounded or missing. Additionally nearly half of the bombers involved in the offensive had suffered some form of damage. Replacement aircraft were now readily available, but the limiting factor was the shortage of trained crews.

Some 1,672 sorties had been flown, and in the course of these the Americans lost 88 bombers over Germany plus many more written off in the UK after landing with severe battle damage. It was convincing evidence that the VIII Bomber Command was not yet ready for deep-penetration raids over Germany without powerful escort fighter protection.