This article was written for a 20th century history class. Aside from an excellent historical summary of the impact of the Mustang on the progress of WWII, it shows that there are some very gifted students of military history out there. Thanks to David for his work!

Abstract

This paper deals with the contributions of the P-51 Mustang to the eventual victory of the Allies in Europe during World War II. It describes the war scene in Europe before the P-51 was introduced, traces the development of the fighter, its advantages, and the abilities it was able to contribute to the Allies' arsenal.

The paper concludes with the effect that the P-51 had on German air superiority, and how it led the destruction of the Luftwaffe. The thesis is that: it was not until the advent of the North American P-51 Mustang fighter, and all of the improvements, benefits, and side effects that it brought with it, that the Allies were able to achieve air superiority over the Germans.

This paper was inspired largely by my grandfather, who flew the P-51 out of Leiston, England, during WW II and contributed to the eventual Allied success that is traced in this paper. He flew over seventy missions between February and August 1944, and scored three kills against German fighters.

Table of Contents

• Introduction
• Reasons for the Pre-P-51 Air Situation
• The Pre-P-51 Situation
• The Allied Purpose in the Air War
• The Battle at Schweinfurt
• The Development of the P-51
• The Installation of the Merlin Engines
• Features, Advantages, and Benefits of the P-51
• The P-51's Battle Performance
• The Change in Policy on Escort Fighter Function
• P-51's Disrupt Luftwaffe Fighter Tactics
• P-51's Give Bombers Better Support
• Conclusion
• Works Cited

Introduction

On September 1, 1939, the German military forces invaded Poland to begin World War II. This invasion was very successful because of its use of a new military strategic theory -- blitzkrieg. Blitzkrieg, literally "lightning war," involved the fast and deadly coordination of two distinct forces, the Wermacht and the Luftwaffe.

The Wermacht advanced on the ground, while the Luftwaffe destroyed the enemy air force, attacked enemy ground forces, and disrupted enemy communication and transportation systems. This setup was responsible for the successful invasions of Poland, Norway, Western Europe, the Balkans and the initial success of the Russian invasion.

For many years after the first of September, the air war in Europe was dominated by the Luftwaffe. No other nation involved in the war had the experience, technology, or numbers to challenge the Luftwaffe's superiority.

It was not until the United States joined the war effort that any great harm was done to Germany and even then, German air superiority remained unscathed. It was not until the advent of the North American P-51 Mustang fighter, and all of the improvements, benefits, and side effects that it brought with it, that the Allies were able to achieve air superiority over the Germans.

Reasons for the Pre-P-51 Air Situation

The continued domination of the European skies by the Luftwaffe was caused by two factors, the first of which was the difference in military theory between the Luftwaffe and the Royal Air Force. The theories concerning the purpose and function of the Luftwaffe and RAF were exactly opposite and were a result of their experiences in World War I. During WW I, Germany attempted a strategic bombing effort directed against England using Gothas (biplane bombers) and Zeppelins (slow-moving hydrogen balloons) which did not give much of a result.

This, plus the fact that German military theory at the beginning of WW II was based much more on fast, quick results (Blitzkrieg), meant that Germany decided not to develop a strategic air force. The Luftwaffe had experienced great success when they used tactical ground-attack aircraft in Spain (e.g. at Guernica), and so they figured that their air force should mainly consist of this kind of plane. So Germany made the Luftwaffe a ground support force that was essentially an extension of the army and functioned as a long- range, aerial artillery.

The RAF, on the other hand, had experimented with ground-attack fighters during WW I, and had suffered grievous casualty rates. This, combined with the fact that the British had been deeply enraged and offended by the German Gotha and Zeppelin attacks on their home soil, made them determined to develop a strategic air force that would be capable of bombing German soil in the next war. Thus, at the beginning of WW II, the RAF was mostly a strategic force that consisted of heavy bombers and backup fighters, and lacked any tactical dive-bombers or ground-attack fighters. (Boyne 21)

The Pre-P-51 Situation

Because of these fundamental differences, the situation that resulted after the air war began was as follows: bombers in enemy territory vs. attack planes. The "in enemy territory" was the second reason for the domination of the Luftwaffe.

At the beginning of WW II, and for many years afterward, the Allies had no long-range escort fighters, which meant that the bombers were forced to fly most of their long journeys alone. (Perret 104)

Before the P-51 was brought into combat, the main Allied fighters were the American P-47 Thunderbolt and the British Spitfire, neither of which had a very long range. The rule-of-thumb for fighter ranges was that they could go as far as Aachen, which was about 250 miles from the Allied fighters' home bases in England, before they had to turn around. Unfortunately, most of the bombers' targets were between 400 and 700 miles from England. (Bailey 2-3)

This meant that bombers could only be escorted into the Benelux countries, northern France, and the very western fringe of Germany. When these unescorted, ungainly, slow, unmaneuverable bombers flew over Germany, they were practically sitting ducks for the fast German fighters.

On the other hand, the bombers were equipped with several machine guns and were able to consistently shoot down some of their attackers. Because of this, "U.S. strategists were not yet convinced of the need for long-range fighters; they continued to cling to the belief that their big bomber formations could defend themselves over Germany." (Bailey 153)

The Allied Purpose in the Air War

The Allies knew that they had to drive German industry into the ground in order to win the war. Since the factories, refineries, assembly-lines, and other industry-related structures were all inland, the only way to destroy them was by sending in bombers. The only way that the bombers could achieve real success was by gaining air superiority, which meant that nearly all of the bombers would be able to drop their bombs without being harassed by fighters, and return home to fight another day.

The problem with this sequence was that the Allies did not have this superiority, (Bailey 28) because their bombers were consistently getting shot down in fairly large numbers, by the German fighters that kept coming. The Allies soon realized that in order to gain this superiority, they would have to destroy more German fighters. In order to destroy the fighters, they would have to be forced into the air in greater numbers. In order to get more German fighters into the air, the more sensitive German industries would have to be attacked with more aggression.

Following this logic, the Allies began an intensified bombing effort that resulted in the famous bombings of Hamburg (July 24-28, 1943) and Ploesti (August 1, 1943), among others. And, indeed, this did cause more fighters to come up to meet and engage the bombers. Unfortunately, the bombers were overwhelmed by the German opposition, and their losses soon began to increase. (Copp 359) The Allied air forces had, in effect, pushed a stick into a hornets' nest, hoping to kill the hornets when they came out, and been stung by the ferocity of their response.

The Battle at Schweinfurt

The culminating point of this backfiring plan was the second bombing raid on Schweinfurt, which occurred on October 14, 1943. Schweinfurt was the location of huge ball-bearing factories that supplied most of the ball-bearings for the entire German military.

The U.S. Eighth Air Force had staged a fairly successful raid on the same city two months earlier, but the second time around, the Germans were ready for them. The official report afterwards said that the Luftwaffe "turned in a performance unprecedented in its magnitude, in the cleverness with which it was planned, and in the severity with which it was executed."

Of the 229 bombers that actually made it all the way to Schweinfurt, 60 were shot down, and 17 more made it home, but were damaged beyond repair. This was a 26.5% battle loss rate for the Americans, while the Germans only lost 38 airplanes the whole day, from all causes. (Boyne 327) This battle was one of the key battles of the war, and undeniably proved to the Allies that the bomber offensive could not continue without a long-range fighter escort. (Copp 444) Even before October of '43, some had begun to realize the need for this kind of fighter. In June, the Commanding General of the Army Air Forces, General Hap Arnold, wrote a memo to his Chief of Staff, Major General Barney Giles, which said:

This brings to my mind the absolute necessity for building a fighter airplane that can go in and out with the bombers. Moreover, this fighter has got to go into Germany. . . . Whether you use an existing type or have to start from scratch is your problem. Get to work on this right away because by January '44, I want a fighter escort for all our bombers from the U.K. into Germany. (Copp 413-414)

The Development of the P-51

In April of 1940, "Dutch" Kindleberger, president of North American Aviation, visited Sir Henry Self, the head of the aircraft division of the British Purchasing Commission, asking if Britain would like to buy some of his B-25 bombers. Self was not interested in buying any more bombers, but was interested in buying a good fighter.

He directed Kindleberger to the Curtiss company, who had a new fighter design, but were too busy building P-40's to do anything with it. Kindleberger went to Curtiss and bought their design for $56,000. He promised Self to have the planes ready by September of 1941. The prototype of the NA-73, as it was called, was ready to fly in October of 1940 and proved to have an excellent design.

The NA-73 had a revolutionary wing design that allowed it to fly at high speeds without adverse compression effects. In other planes, as they approached a certain speed, usually around 450 mph, the air would be flowing around the wing at nearly the speed of sound, putting huge amounts of pressure on the wings, which were unable to deal with the stress. The NA-73 did not have this problem, which meant it could fly safely at much higher speeds.

Another revolutionary idea in the plane was the way heated air from the radiator was dealt with. The NA-73's engineers designed it to expel this air and boost the plane's speed by 15 or 25 mph. The engineers also worked especially hard on making the plane as aerodynamic as possible, and so they positioned the radiator in a new place, made the fuselage as narrow as possible, and set the cockpit low in the fuselage. (Perret 118-119)

It was at this point that an error was made that made the Mustang useless as a long-range offensive fighter. When the NA-73 was mass produced as the P-51, it was powered by a 1250 horspower, liquid-cooled Allison V-1710 engine, which did not have a supercharger and lost performance above 11,800 ft.

At high altitudes air pressure goes down, and so there is less oxygen in a given amount of air, which means that engines do not burn as cleanly, and so lose power. Superchargers compress air before it is pumped into the engine cylinders so that there is enough oxygen for the engine to function well. The early Allison-engined planes did not have the supercharger, and so were limited to low-altitude operations. Even without a high-altitude capability, the Mustang was an impressive plane and was bought in quantity by the RAF. It flew its first mission on May 10, 1942, against Berck-sur-Mer on the French coast. (Grant 17-18)

The Installation of the Merlin Engines

So, for the next eighteen months, the P-51A's continued to fly with the RAF, doing their unexceptional jobs well. After the plane began to go into combat, some people began looking into the idea of fitting the Mustang with a more powerful engine. As the RAF said, it was "a bloody good airplane, only it needs a bit more poke." (Grant 22)

One day, an RAF test pilot was flying a P-51A and the thought occurred to him that the plane could be fitted with a Rolls-Royce Merlin engine, which had about 300 more horsepower and included a supercharger. He suggested it to Rolls-Royce's Chief Aerodynamic Engineer and "both men realized that the combination of this sort of performance with the aerodynamically efficient airframe of the Mustang would revolutionize its potential." (Grant 22) This plan was duly carried out and in November 1943, the first group of P-51B's arrived in England.

Features, Advantages, and Benefits of the P-51

This final Mustang design was superior to anything else that flew at the time. The P-51B had a huge internal gasoline tank capacity (around 425 gallons) and its engine was very economical, using about half the gasoline of other American fighters. This meant its range was 1080 miles and could be extended to 2600 miles when extra drop-tanks were attached to the wings. This made its range far more than any Allied or German fighter's.

As far as performance went, it was superior to all others as well. Neither of the other two main American fighters could compete; the P-47 was too heavy and the P-38 had too many technical problems. The British fighters, the Spitfire and the Hurricane, did not have the range, speed, or power.

But most important was its superiority over the German fighters, the best of which were the FW-190 and the Me-109. The Mustang was 50 mph faster than the Germans up to 28,000 ft., beyond which it was much faster than the FW-190 and still substantially faster than the Me-109.

The Mustang had between 3000 and 4000 lbs. more weight, and so was able to outdive either German plane. The tightness of its turns was much better than the Me-109 and slightly better than the FW-190. (Grant 31, Boyne 389-390, Bailey 153) The result of all of this was that the Allies now had a plane that could go with the bombers all the way to and from their targets, fight and defeat the bombers' German attackers, and not run out of fuel.

The P-51's Battle Performance

So, at the end of 1943 and the beginning of 1944, the new American P-51B's began arriving in England in force. (Dupuy 34) For the first few months of the year, the Mustangs were settling in and having their systems perfected. But by March, the Mustangs had decisively taken control. The arrival and subsequent heavy use of the P-51's had several effects.

The first effect that the Mustangs had was in the running air battles over Europe. Before the beginning of 1944, the bombers had been alone as they approached their faraway targets. But the P-51 changed this, and quickly made an impression on all concerned, enemy and ally alike. For example, on January 11, 1944, the Eighth Air Force launched its first deep penetration of Germany with P-51 coverage.

The bombers' targets were the cities of Oschersleben and Halberstadt, where many German planes were being constructed. When they arrived, there were 49 Mustangs covering a force of around 220 bombers. Even though the bombers suffered heavy casualties, they were able to inflict substantial damage on their target factories.

But the most significant thing about the battle was the shining performance of the P-51's. Since the bombers were attacking two different cities, the Mustang force had to divide into two groups, to support the different attacks. Because of the sensitive nature of the bombers' targets, the Luftwaffe came out in force to defend their factories.

During the ensuing melee, the 49 P-51's shot down 15 enemy planes without suffering a single loss. Major Howard, the group's leader, was credited with four kills within minutes. (Bailey 155) In the grand scheme of things, this battle was insignificant, but it goes to show how much of an advantage the P-51's had over their German counterparts. Considering that these were essentially first-time pilots in the Mustangs' first big battle, this is very impressive.

The Change in Policy on Escort Fighter Function

Another thing happened at the same time as the arrival of the P-51 that greatly aided the Allies and fully utilized the great capabilities of the Mustang. Before the beginning of 1944, the bomber escort's primary function was to fly alongside the bombers, repel any attacks made on the bombers, and generally make sure the bombers stayed safe. Indeed, the motto of the Eighth Air Force Fighter Command was "Our Mission is to Bring the Bombers Back Alive."

One day at the beginning of the year, Jimmy Doolittle, who was the commander of the Eighth Air Force, saw a plaque on the wall with this motto on it and said, "That's not so. Your mission is to destroy the German Air Force. . .Take that damned thing down." (Copp 456) And just days before, in his New Year's Day address to the Eighth Air Force command, General Arnold had said, "My personal message to you-this is a MUST- is to destroy the enemy air force wherever you find them, in the air, on the ground and in the factories." (Copp 456)

What this meant was that the escort fighters were not tied to the bombers anymore, and were free to roam over the countryside and through the towns and cities, destroying at will. The sweeping Mustangs were released to ravage German convoys, trains, antiaircraft gun emplacements, warehouses, airfields, factories, radar installations, and other important things that would be impractical to be attacked by bombers. The fighters were also able to attack German fighters when they were least prepared for it, like when they were taking off or forming up in the air.

What made this possible was the increase in the number of American planes present in Europe. This increase in the number of Allied planes compared to the number of German planes continued to the point that, on D-Day, the Allies used 12,873 aircraft while the Germans were only able to muster a mere 300. (Overy 77) By using this overwhelming numerical advantage, the Allied fighters were able to swamp their opponents in an unstoppable flood of planes.

P-51's Disrupt Luftwaffe Fighter Tactics

This increase in the number of fighters plus the change in fighter philosophy allowed the escorts to cover the bombers while simultaneously ranging far from the bomber stream and destroying all that they could find. This caused the disruption of several effective German fighter tactics that had been used successfully in the past. One of these tactics was the deployment of slow, ungainly German planes that would fly around the bomber formations, out of gun range, and report back on where the bombers were and where their weak spots were.

The free-ranging P-51's soon wiped out these planes. Another popular tactic was to mount rocket launchers on the wings of some of these slower craft, have them linger just out of range of the bombers' guns, and send rockets flying into the bomber formations. These rocket attacks were terrifying to the bomber crews, and often broke up formations, sending some planes to the ground.

Obviously, these attacks also came to a halt. Most importantly, the fast German fighters had to change their attack tactics. Beforehand, they would fly alongside the formations and wait for the right moment to swoop in and attack a bomber. Now, they were forced to group together several miles away from the bombers, and then turn and made a mad rush at the bombers, hoping to inflict sufficient damage on one pass to shoot down some number of enemy bombers. They could not afford to stay with the bombers for very long for fear of being attacked by the Mustangs. (Perret 293)

Indeed, soon after the P-51's entered onto the scene, Hermann Goering, the commander of the Luftwaffe, recommended that the German defensive fighters avoid combat with the P-51, and only attack bomber formations when there were no fighters around. The result of all of this is that the American fighters, led by the P-51's, soon began to gain air superiority.

Not long after Goering's recommendation, a sarcastic Luftwaffe officer commented that the safest flying in the world was to be an American fighter over Germany. (Dupuy 35-36) It is obvious that the P-51, once it was supplied to the Eighth Air Force in great quantities, and unleashed by Doolittle and Arnold's new fighter policies, soon took a heavy toll on German air superiority.

P-51's Give Bombers Better Support

Another profound effect that the increased fighter coverage had was on the most important people, the bombers. After the entrance of the P-51, and the virtual elimination of the German fighter threat, the bombers were in much less danger from German fighters. The result of the decreased danger to the bombers is subtle, but obvious when considered.

Imagine a bomber crew sitting in their cramped plane, unable to move around or evade attack during their bombing run while numerous German fighters speed past their plane firing at them. Second Lieutenant William Brick, the bombardier of a B-17 bomber, tells about the day he flew to Linz, Austria on a bombing run:

" . . . The remainder of the run must be perfectly straight and level, without the slightest deviation, or our five-thousand-pound bomb load will fall wide of the target. No evasive action is possible. . . Then comes the sickening rattle of machine-gun bullets and cannon fire hitting our ship; ignoring the flak from the antiaircraft batteries, German fighter planes zoom in so close that it seems they will ram us. . .

Me109 in Desert Colors

Even at the sub-zero temperatures of this altitude, salty sweat pours down my face and burns my eyeballs. Cursing and praying, I am gripped by the same brand of helpless fear that fliers experience during every bomb run. I feel the terror in my hands, in my stomach, even in my feet. Long after returning from the mission, its effects will remain etched indelibly on my face. . . . "(Brick 61)

This kind of terror experienced by the entire crew of the bombers was sure to affect their concentration and their carefulness. Indeed, "it is an undeniable, if unquantifiable, fact that it is easier to bomb precisely when you know you will probably not be shot out of the sky." (Boyne 341)

Conclusion

In the end, the way that the Allied air forces gained air superiority was by destroying their opposition. The ways in which the fighters were able to destroy German fighters were diverse. The fighters utilized their high speed and maneuverability to fly low-level strafing missions that ranged over large expanses of territory and destroyed many Luftwaffe craft on the ground. This tactic was responsible for the destruction of many dozens of fighters that were unable to go on and fight in the air.

Another way that the Allied fighters destroyed their opposition, and the most important way, was by luring them into the air. Going back to the hornets' nest analogy, the Allies stopped pushing the stick and decided to bide their time until the moment was right. When they did start pushing the stick into the nest again, they were armed with a metaphoric insecticide.

In real life, this "insecticide" was the P-51. Beforehand, the Allies had nothing that could stop the "hornets" and so were helpless to stop their attack. But after they had developed an "insecticide" capable of killing the "hornets," they proceeded to lure the hornets into the open where they could be destroyed.

In reality, the bombers were the lure that brought the Luftwaffe into the air. Using the long-range Mustangs, the Allies were able to make their bombing raids more effective and more deadly to Germany. The approaching end of the Third Reich was enough to get the German fighters into the air to try to stop the bombers from wrecking their war effort.

"Air superiority had been won not by bombing the enemy's factories into oblivion; instead, it was won by the long-range fighter, using the bomber formations as bait to entice the Luftwaffe to fight." (Boyne 338) With the advent of great numbers of the highly superior P-51 Mustang, the German fighters that came up to attack the bombers quickly met their match and were easily repelled by the Mustangs.

Bibliography

Works Cited

Bailey, Ronald H. The Air War in Europe. Alexandria, Virginia: Time-Life Books, 1979. A simple, straight-forward book that includes much background on the development of military aviation, and includes many pictures that chronicle the air war.

Boyne, Walter J. Clash of Wings: World War II in the Air. New York: Simon & Schuster, 1994. A very informative and user-friendly book that dealt with the air aspect of all fronts and theaters of WWII. It includes much data on numerous planes in its appendices.

Brick, William. "Bombardier." American History, April 1995, pp. 60-65. A short magazine article following the story of how a U.S. airman was shot down over Austria, and his subsequent imprisonment by the Nazis.

Copp, DeWitt S. Forged in Fire: Strategy and Decisions in the Airwar over Europe, 1940-1945. Garden City, New York: Doubleday & Company, 1982. A book dealing mostly with the U.S. involvement in the War, with particular emphasis on the politics of the military officials, and how the major strategic decisions were made.

Dupuy, Trevor Nevitt. The Air War in the West: June 1941 to April 1945. New York: Franklin Watts, Inc., 1963. A short, very basic book that did not go into depth, but did cover its material well.

Grant, William Newby. P-51 Mustang. London: Bison Books Limited, 1980. A relatively short book, but one that dealt solely with the P-51, and went into considerable depth concerning its construction and use during WWII and in later conflicts.

Overy, R.J. The Air War: 1939-1945. New York: Stein and Day Publishers, 1980. A fairly dry book that dealt mostly with the economics and generalities of the air war, without dealing too much with the actual fighting.

Perret, Geoffrey. Winged Victory: The Army Air Forces in World War II. New York: Random House, 1993. A good book that covered its topic well, although in-depth discussion of the contributions of the other allies' forces is not dealt with.