The Combined Bomber Offensive 1943 - 1944: The Air Attack on Nazi Germany. L. Douglas Keeney
place until 28 July.
Besides the test on the 200-gallon ferry tanks, there were two other developments in the expendable tank problem during the first phase. One was the testing and provision for procurement of a smaller paper tank of British design. VIII Air Force Service Command’s maintenance division designed a steel tank which was approved by Fighter Command on 29 May. British agencies were asked to manufacture these, but because of production difficulties, the British proposed the substitution of 103-gallon paper tanks which could be pressurized and which had been successfully used on the Mustang. Tests were run on the tank and it was officially approved by the Fighter Command on 26 June. The British began delivery of this tank on 13 July. The third development in the range-extension problem was experimentation with a variety of metal tanks raging in capacity from 75 to 150 gallons. All these were capable of leak-proofing and pressurization but required the installation of certain fixtures on the P-47. Although the solution to the fighter range problem was not reached during the first phase, the need for extending the range was thoroughly realized and progress in design and production was made on both sides of the Atlantic.
The fighter protection given to the heavy bomber operations during the first phase was provided by both RAF Fighter Command and VIII Fighter Command. As a matter of fact, the latter was under the control of RAF Sector Controller until 30 June 1943. All four of the April missions of VIII Bomber Command were given fighter support by Spitfires of the RAF.
The first escort of heavy bombers by P-47 Thunderbolts was furnished on 4 May during the mission against the Ford and General Motors plants at Antwerp. On this mission six squadrons of P-47’s and six of RAF Spitfires were used. The Bomber Command described the support as excellent and attributed the mediocre enemy fighter opposition to the presence of the P-47. During May and June the Thunderbolts escorted the day bombers on at least five other occasions. The other operations of VIII Fighter Command consisted of sweeps, or forays into enemy territory, and diversions designed to give indirect support to the heavies. The P-47’s flew 4727 sorties in 31 operational days during the fires phase and about 30 of them were in support of heavy bombers.
Defense against enemy fighters involved tactical deployment of bombers as well as material developments. Principal tactics were the use of the formation, the diversion, and the feint.
The formation as a defensive measures witnessed much experimentation and development in the ETO in 1943. In the early operations bombing was done by elements of three aircraft in formation and later by squadrons of six. The intensity of enemy fighter attacks forced the bringing together of more aircraft to secure mutual fire support. From January to April 1943 the formations flown were boxes of 12 to 14 aircraft rather widely spaced. The formations were generally loosely flown, for individual evasive action was encouraged. After May the basic group formation was a combat box of 18 to 21 aircraft flown much more tightly than in the earlier period. Such a box ideally flown would occupy 1,200 feet in altitude, 900 feet in breadth, and 600 feet in trail. Actually it was always much larger in breadth and trail. Two or three combat boxes stacked together constituted the combat wing. Experience indicated that three groups was the maximum number that could be practically flown together in a defensive formation. The combat wing was not maintained during the bombing run, since bombing was done by groups. After bomb release the combat boxes would reassemble for support on the route to base.
Formation flying required great skill on the part of the pilots, and the Eighth constantly emphasized the necessity for better training in this specialty at operating altitude. The use of group bombing also influenced another aircrew position. One or two bombardiers in a group became very important because generally all planes released bombs on one sighting operation, that of the bombardier in the lead aircraft. Others simply toggled their bombs on his signal.
The diversion as a defensive tactic was employed by both fighters and bombers. The chief defensive value of the diversion lay in its proper timing to attract enemy fighter action to itself from the main bombing effort of the day. The diversionary force was at times dispatched ahead of the main effort in order to arouse the enemy ahead of time, have him use up his fuel, and so find his fighters grounded when the main attack was delivered. It was also dispatched after the main effort had gone out in order to lessen enemy pressure on a withdrawing force. The diversion was employed at least five times by VIII Bomber Command and several times by VIII Fighter Command during April, May, and June. During the raid on the Erla aircraft plant at Antwerp on 5 April, a force of 25 B-24’s conducted a diversionary sweep over the North Sea and toward the French and Belgian coasts. This measure brought up no fighter opposition, but a similar venture on 4 May was highly successful. On that occasion the bombing objectives were the Ford and General Motors plants at Antwerp. Seventy-nine B-17’s were dispatched on the main effort and 20 B-1’s and 13 B-24’s were dispatched on a diversionary feint toward the French coast. The diversion as well as the main effort was provided with fighter cover. The feint attracted more than 100 fighters (about half the Germans had in the region) and kept many of them airborne so long that they could not attack the main effort. The principal force encountered out 30 enemy aircraft.
VIII Fighter Command engaged in diversionary indirect support of heavies even before it undertook direct close support. On the 17 April raid against Bremen, 76 P-47’s carried out a sweep of the Holland coast while the bombardment mission was in progress.
The diversion not only had defensive value; it gave excellent training to participating air crews. The bomber diversion was but a variation of what has been called the “split-target” technique. This involved the dispatch of strong forces to several different objectives at the same time, thus causing the enemy to disperse his forces. Although practiced during the first phase, the best use of the tactic had to await the build-up of the Eighth to greater strength.
Another defensive variation of the diversion was the feint or fake by the main attack force toward one target with a sharp turn toward the intended objectives at the last moment. Route to and from the target was not left to the groups but was carefully prescribed by higher headquarters.
Except for radar countermeasures, the defensive tactics against flak were fairly well developed by the time of the first phase. These involved selection of operating altitude and route, reduction of bombing run, control of the number of groups bombing together, and evasive action. Further protection from flak was provided by armor plate and the development of special flak curtains and flak suits for crews.
Bombing altitude of heavy bombers during the first phase was generally above 20,000 feet. The lowest reported bombing altitude was 19,000 feet on the Le Mans mission of 20 June, and the greatest, 27,590 feet during a June raid against northwest Germany. Although it is not possible to state an average, it is safe to say that most of the day bombing was from about 23,000 feet. This was high enough to take the planes out of the range of the enemy’s light flak. Bombing altitude, as is the case with many other operational policies, was a compromise. Much better bombing accuracy could have been achieved and many operational problems could have been eased at lower levels. On the other hand, the damage from heavy flak could have been greatly decreased by operating at greater altitudes. The Commanding General of the Eighth stated that the reasons for not going higher were that above 25,000 feet increasing difficulties were experienced with oxygen equipment and with propeller and supercharger action. Operations above 20,000 feet brought to the Eighth a host of problems connected with oxygen, electrically heated flying suits, machine guns, and the functioning of internal combustion engines. Many of the complaints in the United Kingdom about the lack of training of new crews and replacements were due to the altitudes to which the enemy forced operations.
Intelligence and antiaircraft officers played a prominent part in the planning of routes designed to avoid as much flak as possible. With the enemy’s chief emplacements known, not only the best route from base to target could be selected but the best angle of final approach could be charted. Angles of approach and departure were determined by calculating the effectiveness of all possible AA batteries along each 30-degree direction about the target. Charting of such courses became a very important and exacting portion of mission planning. Likelihood of flak damage was also diminished by making the turn along the predetermined axis of attack at the last moment and the production of the bombing run to the shortest possible time commensurate with accurate bombing.
The common method