Between February 2025, 1944, as part of the European strategic bombing campaign, the United States Strategic Air Forces (USSTAF) launched Operation Argument, a series of missions against the Third Reich that became known as Big Week. The planners intended to lure the Luftwaffe into a decisive battle by launching massive attacks on the German aircraft industry. By defeating the Luftwaffe, the Allies would achieve air superiority and the invasion of Europe could proceed. The daylight bombing campaign was also supported by RAF Bomber Command, when they operated against the same targets at night. Arthur Harris resisted contributing RAF forces as it diverted them from the British area bombing offensive. It took a direct order from Air Chief Marshal Sir Charles Portal, Chief of the Air Staff to force Harris to comply.RAF Fighter Command also provided escort for USAAF bomber formations.
Prior to the Big Week, throughout 1943, the U.S. 8th Air Force had been growing in size and experience, and started pressing attacks deeper into Germany. It was believed that the defensive firepower of the B-17 and B-24 bombers, typically ten .50 caliber machine guns or more, would allow them to defend themselves as long as they remained arranged into tight formations, allowing for overlapping fire. In practice this proved less successful; although the bombers did claim a fair number of German fighters, losses among the bombers were unsustainable.
The Schweinfurt-Regensburg missions are a famous example. On August 17, 1943, 230 bombers launched a mission against the ball bearing factories in Schweinfurt and another 146 against the aircraft factories in Regensburg. Of this force, 60 aircraft were lost before returning to base, and another 87 had to be scrapped due to irreparable damage. The Germans claimed 27 fighters lost, serious enough, but paling in comparison to the losses on the part of the US forces. A second raid on October 14, 1943 fared almost as poorly; of the 291 aircraft on the mission, 77 were lost. Daylight missions into Germany were called off in order to rebuild the forces.
The raids were extensively studied by both forces. The Germans concluded that their current strategy of deploying twin-engine designs with heavy armament was working well. Over the winter of 1943/44 they continued this program, adding to their heavy fighter ranks and developing heavier armaments for all of their aircraft. They also pulled almost all of their fighter forces back into Germany, as the majority of their losses were due to fighter actions over forward areas. There seemed to be no point to try attacking the bombers with enemy fighters in the area. The Allied forces came to other conclusions. Schweinfurt demonstrated that the bombers were not able to protect themselves, contrary to earlier thinking, and fighter cover had to be extended over the entire mission. Luckily for the U.S., the P-51 Mustang was just starting to arrive in quantity, an aircraft that had the range to escort the bombers to targets deep within Germany. Over the winter they re-organized their fighter squadrons as Mustangs arrived and longer-range versions of their existing aircraft were developed.
By the time the winter weather started to clear in early 1944, both forces had implemented their plans and were waiting to put them into action. The U.S., expecting a fighter advantage, planned missions that would demand a German response. They decided to make massive raids on the German fighter factories; if the Germans chose not to respond they would be at risk of losing the air war without firing a shot, if they did respond, they would meet fighters in the process. But the Germans needed no provocation, they were ready to meet any future raid with their newly prepared forces. But by up-gunning their fighters they reduced their performance, making them easy targets for the new and unexpected Mustangs.
The Americans flew heavily escorted missions against airframe manufacturing and assembly plants and other targets in numerous German cities including: Leipzig, Brunswick, Gotha, Regensburg, Schweinfurt, Augsburg, Stuttgart and Steyr. In six days, the Eighth Air Force bombers based in England flew more than 3,000 sorties and the Fifteenth Air Force based in Italy more than 500. Together they dropped roughly 10,000 tons of bombs.
During Big Week the Eighth Air Force lost 97 B-17s, 40 B-24s, and another 20 scrapped due to damage. The Fifteenth Air Force lost 90 aircraft and American fighter losses stood at 28. Although these numbers are high in absolute terms, the numbers of bombers involved in the missions were much higher than previously, and the losses represented a much smaller percentage of the attacking force. The earlier Schweinfurt missions cost the force just under 30% of their aircraft; for the Big Week it was under 7%.
U.S. aircrews claimed more than 500 German fighters destroyed, though the numbers were massively exaggerated. The Luftwaffe losses were high amongst their twin-engined Zerstörer units, which suffered heavy losses; also, the Bf 110 and Me 410 Gruppen were decimated. More worrying for the Jagdwaffe was the loss of 17 per-cent of its pilotsnearly 100 were killed. In contrast to the raids of the previous year, the US losses were entirely replaceable and being made good as their industrial might ramped up, while the Germans were already hard pressed due to the war in the East. Although not fatal, the Big Week was an extremely worrying development for the Germans.
The actual damage to the German aircraft industry was fairly limited; during 1944 German aircraft industry was to reach its production high, comparable with the U.S and Soviet industries. However the lack of skilled pilots due to an attritional three-front war was the factor eroding the capability of the Jagdwaffe. The Luftwaffe had to abandon its tactic of "maximum defensive effort" to daylight bombing missions in favor of hit-and-run intercepts. While the Jagdwaffe remained formidable, air superiority had passed irrevocably to the Allies.
The Big Week raids demonstrated that the Luftwaffe's best anti-bomber weapon, twin-engine Zerstörer designs like the Me 410 Hornisse, were appallingly vulnerable against Allied fighters. They were removed from service in the west, passing the defense role primarily to the higher performance single-engine designs.
Due to the effective protection offered by Allied fighters, a change of tactics was introduced: German fighters formed up well in front of the bombers, took a single head-on pass through the stream, and then left. This gave the defending fighters little time to react, and a few shells into the cockpit area could "destroy" a bomber in one pass. In a repeat of earlier RAF strategy, the Luftwaffe also attempted to form up their own version of the "Big Wing", which they hoped would allow them to bring the twins back into combat in the safety of huge number of covering single-engine designs. As had sometimes been the British experience, these formations proved extremely difficult to arrange.
Big Week bolstered the confidence of U.S. strategic bombing crews. Until that time, Allied bombers avoided contact with the Luftwaffe; now, the Americans used any method that would force the Luftwaffe into combat. Implementing this policy, the United States looked toward Berlin. Raiding the German capital, Allied leaders reasoned, would force the Luftwaffe to battle. Consequently, on March 4, the USSTAF launched the first of several attacks against Berlin. From England 730 bombers set out with an escort of 800 fighters. Fierce battles raged and resulted in heavy losses for both sides; 69 B-17s were lost but the Luftwaffe lost 160 aircraft. The Allies replaced their losses; the Luftwaffe could not.
Nevertheless, the new German strategies were proving somewhat effective. The U.S. fighters, kept in close contact with the bombers they were protecting, could not chase down the attacking fighters before they were forced to turn around and return to the bombers. Jimmy Doolittle responded by "freeing" the fighters, allowing them to roam far from the bomber streams and hunt down the German fighters before they could begin to approach the bombers. Though the change was unpopular with the bomber crews, its effects were immediate and extremely effective.
When the combined bomber offensive officially ended on April 1, 1944 and control of the strategic air forces passed to U.S. General Dwight D. Eisenhower, Allied airmen were well on the way to achieving air superiority over all of Europe. While they continued strategic bombing, the AAF turned its attention to the tactical air battle in support of the Normandy invasion.