'Juggler' was a US two-element heavy bomber attack by Major General Frederick L. Anderson’s VIII Bomber Command of Major General Ira C. Eaker’s 8^th AAF against the production centres for Messerschmitt fighters at Regensburg-Prüfening and ball bearings at Schweinfurt (17 August 1943).

The double mission was conceived as an ambitious plan of strategic significance to cripple the ability of the German fighter arm to combat Allied bombers by degrading its current strength in the air and by destroying key elements of fighter manufacture to cripple Germany’s future fighter strength.

The operation was based on a pair of large bomber forces attacking separate targets in close succession in order to dilute the Luftwaffe’s capacity to offer concentrated fighter response, and was also the first 'shuttle' mission in which all or part of a mission landed at a different field and later bombed another target as it returned to its base.

After being postponed several times as a result of adverse weather, this Mission No. 84 was flown on the anniversary of the 8^th AAF’s Mission No. 1, which had involved only a shallow penetration of northern France by 12 aircraft of one bombardment group, escorted by numerous fighters, to attack the railway marshalling yard at Rouen-Sotteville. 'Juggler' launched 376 bombers of 16 bombardment groups against German heavy industry well beyond the range of escorting fighters. Because of the diversion of several bombardment groups to support the 'Torch' landings and the defeat of the Axis forces in North-West Africa, the VIII Bomber Command in England had been limited in size to four groups of Boeing B-17 Flying Fortress four-engine heavy bombers and two groups of Consolidated B-24 Liberator heavy bombers until May 1943. At that time, and in conjunction with the 'Pointblank' directive to destroy the Luftwaffe in preparation for 'Overlord', the B-17 force had been expanded four-fold and was now organised into Brigadier General Robert B. Williams’s 1^st Combat Bombardment Wing (Heavy) and Colonel Curtis E. LeMay’s 4^th CBW(H) which, as a result of their considerable size, on 30 August were redesignated as bombardment divisions (and only a fortnight later air divisions. The 1^st CBW(H), which included all of the original B-17 groups, was based in the Midlands region of England, while the 4^th CBW(H) was based in East Anglia.

The manufacture of Germany’s most important single-seat fighter, the Messerschmitt Bf 109, was based in Regensburg in the Bavarian region of southern Germany and Wiener Neustadt in Austria, while almost all production of ball bearings (used in a host of Germany’s war industries including that part making aero engines) was located in Schweinfurt.

In its original form, 'Juggler' also envisaged an attack on the fighter manufacturing facilities at Wiener Neustadt by B-24 bombers of Lieutenant General Lewis H. Brereton’s US 9^th AAF operating from bases in the Libyan region of North Africa, and all three targets were to be attacked simultaneously to ensure the maximum saturation of the German defences.

The original mission date of 7 August could not be met because of adverse weather conditions, and the B-24 force flew its mission independently on 13 August, whereupon the B-17 mission became a double operation. Using B-17 bombers equipped with the so-called 'Tokyo tanks', carrying 1,080 US gal (4088 litres) in 18 rubberised fuel cells, for greater range, the 4^th BW(H) was to attack the fighter manufacturing plants in Regensburg and then fly on to bases in North Africa, thereby catching the German defences off balance. The 1^st BW(H), following closely on the heels of the 4^th BW(H), was to turn to the north-east and bomb the ball-bearing factories of Schweinfurt, and by doing so catch the German fighter force on the ground rearming and refuelling after its endeavours against the 4^th BW(H).

In effect, the plan called for the 1^st BW(H) to fight its way through to its target, and the 4^th BW(H) to fight its way back from its target.

As a result of their limited range, the Republic P-47 Thunderbolt fighters escorting the bombers could protect their charges only as far as Eupen in German-occupied Belgium, and most of these fighters were assigned to support of the Regensburg mission.

Two supporting attacks were also planned and executed as part of the overall mission plan. The first was a diversionary attack, and involved the bombing of three locations along the French and Dutch coasts: the German airfields at Bryas-Sud and Marck were to be attacked by US Martin B-26 Marauder and British North American Mitchell medium bombers, and the marshalling yards at Dunkirk by other Mitchell bombers, in an effort timed to coincide with the Regensburg attack.

The second supporting element took the form of number of attacks on Luftwaffe fighter airfields at Poix, Lille-Vendeville and Woensdrecht by Hawker Typhoon fighter-bombers of the RAF at the same time as the diversionary attack, and at Poix by two groups of B-26 bombers in the afternoon as the Schweinfurt force was returning.

The 8^th AAF’s bomber operations were calculated on the basis of one to two hours of climb and assembly into formations factored into mission lengths. In addition the mission endurance for the Regensburg force was estimated at 11 hours, so that commanders had only a 90-minute 'window' in which to launch the mission and still allow the B-17 bombers of the 4^th BW(H) to reach North Africa in daylight.

Planning indicated a take-off window from dawn at about 06.30 to 08.00 before the mission would have to be cancelled. At dawn on 17 August, with the crews already on board their aircraft, England was covered in fog. The mission take-off was delayed to 08.00, when the fog had cleared sufficiently over East Anglia to allow the 4^th BW(H) to make instrument take-offs. Although the timing of the mission was deemed critical to its success, the Regensburg force was ordered to take-off, even though the 1^st BW(H) remained grounded on its Midland bases by the adverse weather. By the time the fog over the Midlands had lifted sufficiently, the Regensburg force had already reached the coast of the German-occupied Netherlands, suggesting already that the German fighter force would have the time attack the 4^th BW(H), then land, rearm and refuel before taking-off in sufficient time to tackle the 1^st BW(H).

As a result the launch of the Schweinfurt force was further delayed to give the escort fighters of Brigadier General Frank O’D. Hunter’s US VIII Fighter Command time to return to base and rearm and refuel for a second escort mission. Thus the 1^st BW(H) took off more than three hours behind the 4^th BW(H).

The Regensburg task force was led by LeMay, and comprised seven B-17 groups totalling 146 aircraft: the 96^th, 388 and 390 Bombardment Groups of the 403^rd Provisional Combat Bombardment Wing with 21, 21 and 20 aircraft respectively; the 94^th and 385^th Bombardment Groups of the 401^st Provisional Combat Bombardment Wing with 21 aircraft each; and the 95^th and 100^th Bombardment Groups of the 402^nd Provisional Combat Bombardment Wing with 21 aircraft each. All but one of these groups flew a 21-aircraft combat box tactical formation. The groups were organised into three larger 'provisional combat wings', three groups in a V-formation wing box leading the procession, followed in trail by two wing boxes of two groups each in echelon formation with one group leading and the second trailing at lower altitude.

Escort for the Regensburg task force was provided first by the 37 P-47 fighters of the 353^rd Fighter Group, and then by the 50 P-47 fighters of the 56^th Fighter Group.

About 15 minutes after it crossed the coast at 10.00, the Regensburg force encountered the first German fighter response, which continued with growing intensity nearly all the way to the target area. Several factors weighed against the Regensburg force in this air battle. The arrangement of two groups instead of three in the two following provisional wings meant 33% fewer guns available to each for their mutual defence, and made them more likely targets. The overall length of the task force was also too great, with the last wing formation 15 miles (24 km) behind the first and nearly out of visual range. Two groups of P-47 fighters had been entrusted with the task of escorting the force to the Dutch/German border, but only one arrived at the rendezvous point on time, covering the lead wing, and the second arrived 15 minutes late. Finally, both groups of P-47 fighters were forced to turn back to base after only 15 minutes of escort duty, without engaging the German interceptors. The last provisional wing in the task force was therefore left without any fighter protection at all.

After 90 minutes of combat the German fighter force broke off the engagement as its aircraft were low on fuel and ammunition. By then at least 15 bombers had been shot down or fatally damaged, 13 of them aircraft of the trailing formation. Flak was light over Regensburg and the visibility clear, however, and of the remaining 131 bombers, 126 dropped 298.75 tons of bombs on the fighter factories with a high degree of accuracy at approximately 12.00. The surviving aircraft of the Regensburg force then turned south to cross the Alps, confronted by only a few fighters which were soon forced to disengage by lack of range. The German force had not been prepared for this contingency, but they were also in the process of rearming to meet the Schweinfurt force, then forming over East Anglia. Even so, two damaged B-17 bombers turned away from the Regensburg task force and landed in neutral Switzerland, where their crews were interned and their bombers confiscated. Another crash-landed in Italy and five more were forced down by lack of fuel into the Mediterranean Sea. In all 24 bombers were lost, nine of them aircraft of the 100^th Bombardment Group, and more than 60 of the 122 survivors which arrived in Tunisia had suffered battle damage.

The 1^st BW(H), commanded and led by Williams, comprised nine B-17 groups organised into four provisional combat wings: the 91^st Bombardment Group, 101^st Composite Group and 381^st Bombardment Group of the 201^st Provisional Combat Bombardment Wing with 18, 19 and 20 aircraft respectively; the 351^st Bombardment Group, 306^th Composite Group and 384^th Bombardment Group of the 202^nd Provisional Combat Bombardment Wing with 21, 20 and 18 aircraft respectively; the 306^th, 305^th and 92^nd Bombardment Groups of the 203^rd Provisional Combat Bombardment Wing with 21, 20 and 20 aircraft respectively; and the 397^th Bombardment Group, 103^rd Composite Group and 303^rd Bombardment Group of the 204^th Provisional Combat Bombardment Wing with 18, 17 and 18 aircraft respectively.

It was the fact that the 1^st BW(H) had a sufficient number of aircraft and trained crews which made it possible to create a force with four wing boxes: this was accomplished by each of the nine groups providing one of its squadrons to three 'composite groups' created for this mission, and distributing these makeshift groups among the others to form a fourth wing box.

While the individual group boxes were not as large as usual (only one group had the full 21 aircraft and the smallest box had only 17), the total force amounted to 230 bombers. The Schweinfurt force was further divided into two task forces of two wings (six groups) each and was more than 20 miles (32 km) long.

The Schweinfurt task forces followed the same route as the Regensburg force. Because of the mission’s delayed start, the RAF added eight squadrons of Supermarine Spitfire fighters (72 and 24 aircraft of Nos 11 and 83 Groups) to escort the Schweinfurt force as far as Antwerp, where P-47 units would take over and escort it to Eupen.

The order for the mission specified that the bombers would fly at altitudes between 23,000 and 26,500 ft (7010 and 8075 m), but approaching the coast of the Netherlands at 13.30, the force was confronted with developing cloud masses not present earlier in the day. The commander of the 1^st BW(H)'s first task force estimated that the bombers would not be able to climb over the clouds and elected to fly under them at 17,000 ft (5180 m), so increasing the bombers' vulnerability to fighter attack.

The first German attacks began almost immediately and employed tactics different from those used against the earlier mission. The lead wing was attacked continuously in head-on attacks by both Bf 109 and Focke-Wulf Fw 190 fighters, and although the RAF escorts claimed eight victories they were forced to return to base early in the engagement. The 78^th and 4^th Fighter Groups, with 40 and 48 P-47 fighters, arrived five and eight minutes late respectively, and despite some individual combats, they too were forced to break off virtually as soon as they arrived.

Over Germany fighter aircraft, many of them equipped for launching air-to-air unguided rockets, joined the battle as more than 300 fighters from 24 bases opposed the raid. The attacking force diverged from the morning raid’s route at Mannheim and Worms, alerting the German defenders that the target was Schweinfurt.

Losses among the 57 B-17 bombers of the leading wing were so severe that many among its airmen considered the possibility that the wing might be annihilated before reaching the target. However, 15 miles (24 km) from Schweinfurt the opposing fighters, after shooting down 22 bombers, disengaged and landed to rearm and refuel in order to attack the force on its way out.

Some 5 miles (8 km) from Schweinfurt the Flak guns began firing an effective barrage into the path of the bomber force. At 14.59 some 40 B-17 bombers remained as the leading wing dropped its bombs on the target area, which contained five factories and 30,000 workers, followed over a 24-minute period by the remainder of the force. Each wing found increasingly heavy smoke from preceding bomb explosions a hindrance to accuracy. Some 183 bombers dropped 424.3 tons of bombs, including 125 tons of incendiaries. Three bombers had been shot down by Flak over Schweinfurt.

Some 15 minutes after leaving the target area, each task force circled over Meiningen to rebuild its formations, then continued to the west in the direction of Brussels. At about 15.30 the German fighters renewed their attacks, concentrating now on damaged bombers. Between 16.30 and 17.00 86 P-47 and 95 Spitfire fighters, the former comprising 51 and 42 machines of the 56^th and 353^rd Fighter Groups and the latter 72 and 23 machines of Nos 11 and 83 groups, arrived to provide withdrawal support, claiming 20 fighters shot down, but eight more bombers were lost before the force reached the North Sea, where three more crash-landed. The Schweinfurt force lost a total of 36 bombers.

In overall terms, 55 bombers and 552 men were listed as missing as a result of the August 17 double mission. About half of the missing men survived to become prisoners of war, and 20 were interned in Switzerland. Of the lost aircraft, 60 succumbed over German-controlled territory, Switzerland, or ditched at sea, with five crews rescued. There were seven dead and 21 wounded on board bombers which returned to base.

The 60 aircraft lost on a single mission more than doubled the highest previous loss at that time. There were also another 55 to 95 aircraft which had suffered severe damage, and many of these (especially those which reached French Algeria, where the repair facilities were rudimentary) proved to be beyond economical restoration to fighting condition and were therefore scrapped. Three P-47 fighters of the 56^th Fighter Group and two Spitfire fighters of the RAF were shot down attempting to protect the Schweinfurt force.

On the other side of the coin, Spitfire pilots claimed 13 German fighters shot down and P-47 pilots claimed 19. Gunners on the bombers claimed 288 fighters shot down, but German records showed the loss of only 25 to 27 fighters.

In Regensburg all six main workshops of the Messerschmitt factory were destroyed or severely damaged, as were many supporting structures, the latter including the final assembly facility. In Schweinfurt the destruction was less severe but still extensive. The two largest factories, those of Kugelfischer & Co. and Vereinigte Kugellager Fabrik I, suffered 80 direct hits. Some 376,750 sq ft (35000 m²) of buildings in the five factories were destroyed, and more than 1,076,425 sq ft (100,000 m²) suffered fire damage. All but the Kugelfischer factories sustained major fire damage to their machinery when incendiaries ignited the machine oil used in the manufacturing process.

The German minister of armaments and war production, Albert Speer, reported an immediate 34% loss of production, but the production shortfall and the actual loss of bearings were offset by the location of major surpluses throughout Germany in a search immediately after the raid. The industry’s infrastructure, while vulnerable to a sustained campaign, was not vulnerable to destruction by a single raid. Speer indicated that the two major US flaws in the planning and execution of 'Juggler' were first the division of the attacking force instead of a more threatening single attack on the ball-bearing factories, and second the failure to follow the first attack with repeated efforts.

While production of fighters and ball bearings was only marginally affected, the Germans learned their lesson about the vulnerability of high-value pinpoint targets and started them on the path to greater dispersal of vital war industries, the most important of them into mines and other deep underground facilities immune to the effects of conventional bombing.

German civilian losses in both halves of the raid totalled 203 persons.

The Schweinfurt mission in particular foretold the extreme vulnerability of deep-penetration attacks of targets within Germany without adequate long-range escort. The 1^st Bombardment Wing was over German-occupied territory for 3 hours 30 minutes, of which 2 hours 10 minutes, including all of the time spent over Germany itself, found it without any fighter support. When the second attack on Schweinfurt was made on 14 October, the loss of 60 our of 291 B-17 bombers, representing 20.6% of the attacking force, led to the suspension of deep-penetration raids for five months.