London, England · July 8, 1941

On this date in 1941, five months before the United States was drawn into World War II, the Boeing B‑17 Flying For­tress was flown in com­bat for the first time, this by the Royal Air Force in an attack on the North Ger­man port of Wilhelms­haven. The first pro­duc­tion model, the Boeing B‑17B, was flown on June 27, 1939, and by year’s end 25 of these high-per­for­mance, four-engine heavy bombers were in Amer­ica’s air fleet. By the end of World War II, nearly 13,000 “Forts” would see ser­vice in the RAF and U.S. Eighth, Ninth, Twelfth, and Fifteenth Army Air Forces.

The later-model B‑17s—there were six in all—had a top speed of just under 300 mph, a range of 2,000 miles, and carried a 10- or 11‑man crew. Like the twin-tailed Consoli­dated B‑24 Libe­rator and the British-built Avro Lan­caster, the B‑17 was at the heart of the Anglo-Ameri­can stra­tegic bombing cam­paign in Europe. According to a state­ment by the U.S.-British Combined Chiefs of Staff in January 1943, the objec­tive of the bombing cam­paign was to destroy and dis­locate the Axis “mili­tary, indus­trial, and eco­no­mic system, and [under­mine] the morale of the people to a point where their capa­city for armed resistance is fatally weakened.”

In carrying out its role, the heavy defen­sive arma­ments of the B‑17 limited bomb loads to 2‑1/2 tons per plane, which meant that raids over Axis-occu­pied Europe con­sisted, on any single mis­sion, of hun­dreds and later several thou­sand of these war­birds, accom­panied by a thou­sand-fighter escort. The bombers carried a deadly mix of high-explo­sive bombs and in­cen­di­ary bombs that devas­tated not just popu­la­tion cen­ters like Ham­burg (mid-1943) and Berlin (a turn­about on the Lon­don Blitz of 1940–1941) but also key eco­no­mic and mili­tary choke­points; for example, classifi­cation/­mar­shal­ling yards where troop and freight/­goods cars were formed into trains, rail lines, high­ways, and bridges; air­craft and ar­ma­ment fac­tories; ball bearing plants; and oil and arti­fi­cial fuel refineries and tank farms.

The theory that round-the-clock bombing by the RAF (by night) and the USAAF (by day) would seriously under­mine Germany’s defenses, devas­tate the Ger­man eco­no­my and work­force, demoralize civilian morale, and force the country’s leadership to the nego­ti­a­tion table like it did Italy (more or less)—all with­out a bloody ground inva­sion—did not mate­ri­alize. But applied to Japan’s Home Islands, the theory worked up to a point, nudged in the end by two nuclear bombs.

Allied Heavy Bombers Over Germany and Their Escorts

U.S. Eighth Air Force Boeing B-17 Flying FortressRAF Avro Lancasters

Left: A B-17 Flying Fortress of the U.S. Eighth Air Force sta­tioned at Bassing­bourn, Eng­land. Unable to con­duct ground opera­tions on the Euro­pean con­ti­nent until Allied strength was suffi­cient for a full-scale inva­sion, British and Amer­ican war planners based their grand stra­tegy on a pro­tracted cam­paign of aerial bom­bard­ment of Ger­many’s indus­trial sites and civil­ian areas in order to bring the Third Reich to its knees. Allied heavy bombers, com­bined with night-navi­gation and pre­cision-bombing tech­niques, proved devas­tatingly effec­tive. Of Germany’s 25 largest popu­lation cen­ters (500,000 or more resi­dents) Leipzig suffered the least (at 20 per­cent) and Bochum the most (83 per­cent). Ham­burg was 75 per­cent destroyed; Mainz, Dues­sel­dorf, Cologne, Han­no­ver, and Mann­heim suffered 60 per­cent or better; and a third of the Nazi capi­tal, Berlin, lay in ruins at war’s end.

Right: Three RAF Avro Lancaster B.Is based at Wadding­ton, Lincoln­shire, fly above the clouds, Septem­ber 29, 1942. Intro­duced into ser­vice in February 1942, 7,377 of these four-engine “Lancs” were built. They became the main heavy bomber used by the RAF as well as the most famous and suc­cess­ful of the war’s night bombers in con­trast to the USAAF heavy bombers that were used mostly in daylight raids over Europe.

Republic P-47D ThunderboltNorth American P-51D Mustang

Left: First flown on May 6, 1941, 15,660 of these Repub­lic P‑47 Thunder­bolt air com­bat, ground attack, and bomber escorts were built. Rugged and armed with eight .50 cali­ber ma­chine guns, these jug-shaped fighters were powered by a Pratt & Whit­ney R‑2800 radial engine for a maxi­mum speed of 433 mph at 30,000 ft. They were a good match for the Luft­waffe’s Messer­schmitt Bf 109s and Focke-Wulf Fw 190s. But even out­fitted with extra fuel in belly tanks, P‑47s in their escort role could only accom­pany Allied heavy bombers from Eng­land to the Ger­man border before they were forced to turn back for home.

Right: North American P‑51 Mustangs were used in air com­bat, ground attacks, preci­sion bombing, and long-range bomber escort service. Over 15,000 P‑51s in 12 major pro­duc­tion vari­ants were built. The P‑51 entered ser­vice at the end of 1943. Equipped with a Rolls-Royce Mer­lin V engine that could propel it at 441 mph at 29,000 ft, the P‑51 and the Lock­heed P‑38 Lightning vir­tually swept the Luft­waffe from the sky in time for June 1944’s Normandy landings. In this photo the P‑51 is wearing its Nor­mandy in­va­sion stripes. P‑51s de­stroyed 4,950 enemy air­craft in the air, more than any other fighter in Europe.

U.S. Air Force’s Presentation of the Schweinfurt and Regens­burg Raids, August 17, 1943