By February 1944 the Allies had a deadline. The invasion of France was coming in the summer, and it could not succeed with the Luftwaffe still able to contest the skies over the beaches. The German fighter force had to be broken first. The weather over Germany finally cleared on 20 February, and the Allied air forces launched the most concentrated bombing offensive they had yet attempted.

It was officially Operation Argument. The crews called it Big Week. Over six days, American and British bombers struck aircraft factories across Germany by day and by night. The targets were the factories. The real prize, as several historians have argued since, was the German fighter pilots who rose to defend them.

Bait for the Luftwaffe

The plan targeted the German aircraft industry in central and southern Germany. Planners expected daily losses of between 7 and 18 per cent. Major General Frederick Anderson was prepared to lose a large share of the bomber force if that was the price. The attacks began with an RAF night raid on Leipzig, followed on 20 February by American raids on factories and airfields at Leipzig, Tutow and Brunswick.

Some historians argue that the factories were never the main point. The Luftwaffe had to defend them, and every German fighter that came up to meet the bombers could be shot down.

Doolittle Unleashes the Fighters

A crucial change had come a few weeks earlier. When Jimmy Doolittle took command of the Eighth Air Force in January 1944, he ended the rule that escort fighters must stay tied to the bombers at all times. Instead, fighters could sweep ahead of the formations and hunt German fighters wherever they found them. Many bomber crews disliked losing their close escort, but the change worked. With long-range P-51 Mustangs and P-47 Thunderbolts on the attack, the German interceptors were now the hunted as well as the hunters.

The Operations Room animates the first day of Big Week, when the USAAF and RAF hit Leipzig. Video: The Operations Room

Ten Horsepower

The first day produced one of the most moving stories of the air war. The B-17G nicknamed Ten Horsepower was attacked by German fighters. The co-pilot, Flight Officer Ronald Bartley, was killed, and the pilot, 1st Lt. Clarence Nelson, was badly wounded. The crew brought the bomber back to its base at RAF Polebrook. Ordered to bail out, most of the crew did. The navigator, 2nd Lt. Walter Truemper, and the flight engineer, Staff Sergeant Archibald Mathies, refused to leave their wounded pilot and tried to land the aircraft themselves. On the third attempt it crashed, killing all three. Truemper and Mathies were awarded the Medal of Honor posthumously.

The Nijmegen Tragedy

Big Week had a dark side too. On 22 February, cloud forced a recall of 333 B-17s, and 177 B-24s went looking for targets of opportunity. In error they bombed the Dutch cities of Nijmegen, Arnhem, Enschede and Deventer. Between about 880 and 900 Dutch civilians were killed, most of them in Nijmegen. An investigation followed, and all missions on 23 February were cancelled.

What Big Week Achieved

The raids resumed on 24 and 25 February, with Schweinfurt, Augsburg and Regensburg among the targets. The RAF night attack on Augsburg on 25/26 February destroyed roughly 60 per cent of the city's industrial area. Elsewhere, results were patchy: the Schweinfurt raid caused little damage because of inaccurate bombing.

As a blow to production, Big Week largely failed. German fighter output actually rose during 1944 as factories were dispersed and other aircraft types were cut. As a battle of attrition, it succeeded. The Luftwaffe lost 262 fighters and nearly 100 fighter pilots killed in six days, and experienced pilots were the one thing Germany could not replace, with the Eastern Front demanding its share. Claims by US gunners and fighter pilots exceeded actual German losses by around 40 per cent, but the real losses were heavy enough.

Big Week seen from the German fighter pilots' side. Video: The Operations Room

By June 1944, when Allied troops landed in Normandy, the Allies held air superiority over the beaches. Big Week did not win it alone, but it was the week the Luftwaffe's day fighter force began to bleed out.

A CBS World News Today broadcast from February 1944, as Big Week began. Video: Old Broadcast

Sources: Wikipedia (Big Week, Jimmy Doolittle), This Day in Aviation, McFarland and Newton (via Wikipedia)