Published Airpower Journal -
Summer 1994
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On 7 June 1944, under the German code name Drohende Gefahr West ("Imminent Danger West"), the Luftwaffe started to move a large percentage of its fighter forces forward to airfields closer to the Normandy beaches.1 The movement had been delayed one day due to the widespread belief that the Normandy invasion was a feint. The Germans expected the real invasion to take place at the Pas de Calais. Less than two weeks later, those same units--bloody and largely decimated--returned to Germany to shore up the defense of the Reich.2 Meanwhile, the German Fifteenth Army, also being held for an invasion at the Pas de Calais, had attempted to move towards the Normandy landing sites. Its movement was hampered by destroyed bridges and devastating and relentless attacks by Allied air power.3
The purpose of this article is to examine the air campaign that ensured the success of the Normandy invasion (Operation Overlord). Too often this campaign is relegated to the backwaters of larger studies dealing with the strategic bombing of Germany. Further, analysis of this campaign often becomes a discussion of the personalities and ideological issues that framed the "transportation plan" versus the "oil plan." We will not ignore these important issues. Rather, we will attempt to place them in the larger context of the need to ensure the success of the largest amphibious landing ever attempted.
The relevance of studying this campaign is not to glean tactical or even operational guidelines for future campaigns. Rather, the lessons learned from this operation focus on the process that Allied planners used to put together such a massive undertaking. It is my contention that the process is what is important and that process applies to operational-level campaign planning today. In that light, this article analyzes the Overlord air campaign using a current air campaign planning model.4 It looks at the objectives of the campaign and at the strategy that planners chose to achieve those objectives, including why they selected one of many possible choices. It then turns to the planners' center of gravity5 analysis that identified key chinks in the German armor and how planners weighed the pros and cons of attack versus denial or exploitation of those chinks. The article then turns to the actual campaign plan itself. It looks at counterair operations, strategic attack operations, interdiction plans, and air support plans for the invasion.
There was no named "campaign plan" for air support of the invasion. Operations Pointblank,6 Crossbow,7 and Argument8 were all previously conceived and executed to at least partially achieve Overlord objectives. In like manner, there is no particular "starting" or "ending" point to the invasion support air plan. This study examines the period from January 1944 through the consolidation of the beachhead on 12 June 1944.
Determining the objective is the most important part of campaign planning. The primary air mission in the air plan for Overlord, issued on 23 April 1944, was "the attainment and maintenance of an air situation in which the German Air Force would be incapable of interfering with the Allied landings."9
In the directive issued to the commanders of his strategic air forces on 17 April 1944, Gen Dwight D. Eisenhower listed the tasks for the Allied Air Forces: to assist the Allied armies in establishing a lodgment; to maintain the combined bomber offensive; to secure and maintain air superiority; and to attack rail communications in the Overlord area.10 These tasks mirror those set forth in Field Manual (FM) 100-20, Command and Employment of Air Power, which was formulated largely on the experiences of the US Army Air Forces in the North African campaign of November 1942-May 1943.11
There is a fine line between objectives and strategy. What one wants to achieve is largely predicated on how it can be achieved. While there was a large degree of unanimity on the Overlord objectives, there was strong disagreement on the means to attain these objectives. The disagreements centered on two areas. The first was over the method of accomplishing the counterair objective. This disagreement was rooted in whether it was more efficient to destroy the Luftwaffe through destruction of the means of production or to destroy it in aerial combat.12 Even the latter school had two branches. One branch claimed that the quickest way was through air-to-air combat, while the opposing view was that it was quicker to destroy the Luftwaffe on the ground.13 For Overlord, this area of disagreement focused on the conception of Air Chief Marshal Sir Trafford Leigh-Mallory, commander in chief of Allied Expeditionary Air Forces (AEAF), that the Luftwaffe would be destroyed in one climactic air battle over the Normandy beaches. This was opposed by the commanding general of the United States Strategic Air Forces (USSTAF),14 Carl A. Spaatz, who wanted to decimate the Luftwaffe through continuance of the strategic bombing campaign against Germany.15
The second area of disagreement over strategy centered on how the landing beaches were to be isolated from German reinforcement. One side claimed the battlefield should be isolated by attacks on the enemy railway system, specifically railroad marshaling yards.16 This plan became known as the transportation plan (discussed more fully later). The opposing view believed that the most effective means of isolating the beachhead was through a classic interdiction campaign of attacking locomotives, supply columns, and the like as they moved to counter the Allied invasion.17
Determining the enemy's center of gravity is second in importance only to determining the operation's objectives. A useful tool in this effort is to disaggregate the enemy into categories of potential centers of gravity, analyze individual target sets within those categories, then select those specific nodes within the target sets that promise to offer the highest degree of leverage. As mentioned earlier, Allied air planners for Overlord did not specifically follow this process, though, as will be shown, the outcomes were the same. The important point is that they did have a means of analyzing the enemy to find the significant chinks in his armor.
There is no evidence that Allied forces attempted to attack German leadership directly. However, they did make a concerted effort to blind the enemy. The primary area of effort was the coastal radar installations that spread from Norway to Spain. In attacking these sites, the Allies encountered a problem that was to plague them in many areas of the preinvasion air campaign: how to attack critical targets in the invasion area without highlighting Normandy as the specific landing site. The Allies orchestrated an elaborate deception plan to delude the Germans into identifying the Pas de Calais as the invasion site.18 Allied air attacks had to reinforce this idea. To achieve this, planners developed a "2-for-1" strategy in which two targets outside the invasion area would be struck for every one inside the invasion area.19
Planners identified as the critical command and control (C2) nodes those radar installations between Ostend, Belgium, and the Channel Islands because these facilities could not only identify the invasion fleet and be used to sight coastal guns against the ships but could also be used to guide enemy night fighters. This was considered a special hazard to the planned airborne assault force.20
The planned attack against German logistics was part of the overall campaign against the German industrial system. This was part of the ongoing debate over the use of the heavy bombers. The Combined Bomber Offensive (CBO), formerly authorized on 10 June 1943 and code-named Pointblank, had as its mission "to conduct a joint US-British air offensive to accomplish the `progressive destruction and dislocation of the German military, industrial and economic system, and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened."21 Further, the CBO was given the task of weakening the Germans so "as to permit initiation of final combined operations on the Continent."22 The primary intermediate objective of the CBO was the destruction of the Luftwaffe and the achievement of air superiority. This served two purposes. First, air superiority would allow for the successful invasion of the Continent. Second, air superiority would permit the strategic bombing of German industrial and economic targets without prohibitive losses.
This priority scheme did not necessarily sit well with senior air force commanders. They believed that unremitting air attack against the vital industrial and economic targets in Germany would be sufficient to cause her capitulation.23 They understood the need for air superiority, but only as a means to an end. That end was more effective strategic bombardment of Germany.24 However, for the US and British political and military leadership, the goal--the unconditional surrender of Germany--could only be achieved through the fields of France.25 Infrastructure
The primary purpose of the Allies' attack against infrastructure was to isolate the battlefield--that is, to prevent (or at least to slow) movement of enemy troops or supplies to the battlefield. As discussed later, preparation of the battlefield--that is, concentrated direct attack on German forces in and around the Normandy landing sites--was held to just a few days before the invasion. This was necessary to prevent the Germans from identifying the location of the invasion. The basic disagreement was over the means of isolating the battlefield. Should classic interdiction against either rail centers, bridges, or moving locomotives be used to attempt to physically stop movement into the area of interest? Or should the transportation system be brought to a halt by cutting off their supply of fuel?
The Transportation Plan. The primary proponents of the transportation plan were Air Chief Marshal Sir Arthur W. Tedder and a civilian scientist, Solly Zuckerman. The original plan developed by planners at Supreme Headquarters, Allied Expeditionary Forces (SHAEF)26 called for bombing 20 railroad targets 50 to 60 miles from the invasion area. Zuckerman felt the plan insufficient and devised one calling for attack against 76 railway centers in France, Belgium, and western Germany.27
The rationale for bombing the rail centers was twofold. First, Zuckerman believed that destruction of the marshaling yards would decrease the volume of rail traffic and channelize it to a few key areas. This would prevent the German ground forces from rapidly moving forces to counter the invasion and also expose those forces to air attack. The second rationale was even more compelling for Zuckerman and Tedder, his boss. They believed that "attacks on rail centers in western Germany would contribute both to reducing the volume of military traffic flowing westward and to restricting and ultimately halting industrial activity in the Reich."28 These ideas grew out of Zuckerman's analysis of the bombing of the Sicilian and Italian railways in 1943.29
Opposition to Zuckerman's railway centers plan was quick to rise. The arguments centered on two key issues. The first dealt with the use of heavy bombers of Eighth Air Force and RAF Bomber Command. Zuckerman's plan would require extensive use of these to attack the rail centers "for a substantial period prior to the early June landings."30 From the RAF perspective, its bombers were engaged in night area bombing and were not trained to achieve the necessary accuracy required for hitting a somewhat smaller target.31 For USSTAF, the issue was diversion of the heavies away from the critical battle for Germany and air superiority that was yet to be decided.32 A counterproposal placed the emphasis on interdicting German forces through the use of medium bombers and fighter-bombers of the tactical forces (Ninth Air Force and the RAF Second Tactical Air Force). Tedder's plan had envisioned the use of fighter-bombers to augment the attacks against the rail centers, particularly as the invasion drew near.33
Operation Chattanooga Choo-Choo, starting in late May 1944, was an outgrowth of sporadic attacks conducted earlier primarily against Luftwaffe aircraft on the ground but encompassed attacks against trains, barges, motor transports, and barracks.34
The Oil Plan. The controversy over the transportation plan also centered on the most effective means of bringing the entire war to an end. Again, this concerned the use of the heavy bombers in the oil plan, which was not strictly part of the Overlord air plan. However, the controversy over the transportation plan versus the oil plan promised to have great impact on the invasion preparation.
The main advocate of the oil plan was USSTAF commander Spaatz, but the idea of hitting German petroleum facilities dated from Air War Plans Division-Plan 1 (AWPD-1) Munitions Requirements of the Army Air Forces.35 The argument for the advocates of the oil plan centered around the vulnerability and scarcity36 of Germany's fuel supply, and the fact that the machinery used by the Germans to produce synthetic products "was complex, very expensive, not at all mobile, and difficult or impossible to hide."37 In addition to the ease with which they could be attacked, the targets were relatively out in the open, and thus civilian casualties would be minimized. However, the primary reason Spaatz advocated oil was his belief that the Luftwaffe would rise to defend those plants.38 Spaatz maintained that the success of the invasion centered around Allied control of the air.39
The Bridge Plan. The final disagreements over the interdiction centers of gravity concerned the destruction of bridges leading into the invasion area. Prior to the spring of 1944, destruction of bridges was considered too difficult. The construction of the bridges themselves, the presence of antiaircraft defenses, and the high tonnage required all argued against bridge attack.40 Spaatz, however, conducted trials in early 1944 that showed that bridges could be successfully attacked at not too high a cost. Additionally, information arriving from the Italian theater confirmed the viability and high payoff that could be expected from destroying bridges.41 Finally, 21 Army Group Headquarters requested air destruction of key bridges to isolate the invasion area.42
The two primary concerns over population as it related to the Overlord air plan were attempts to minimize French civilian loss of life and the diversion of heavy bombers from RAF Bomber Command. As shown with the transportation plan, a large concern was expressed by air planners and civilian leadership alike on the potential side effects the bombing would have on the civilian populace.43
The primary target set of German fielded forces included those forces located in the immediate area of the landing beaches. As with command and control, planners faced the dilemma of attacking targets of critical importance to the success of the invasion, yet not giving away the location of the invasion. This necessitated continued use of the "2-for-1" strategy.
Of most concern to the planners were the coastal guns. They identified some 50 batteries, containing two to six guns apiece, ranging in size from 105 to 400 millimeters, that commanded the sea approaches to the invasion beaches. These guns posed a potentially devastating threat to the assault craft. The difficulty was that these batteries were camouflaged, cleverly concealed, and buttressed with steel and concrete. Air planners, believing that air-delivered bombs would be ineffective against these casements, planned on attacking the crews that manned them shortly before the invasion. Additionally, air planners counted on the prelanding naval bombardment to silence the guns.44
Additional target sets were underwater obstacles and mines. Leigh-Mallory urged a plan of using fighter-bombers to attack these obstacles. Again, however, the concern over highlighting Normandy as the invasion site overshadowed the benefits that might be gained. Finally, air planners were faced with the difficulty of isolating the beaches from immediate reinforcement by German troops in the vicinity of Normandy and of securing key bridges that would be necessary for the Allied advance inland. The proposal to use airborne and glider-landed troops was opposed by Leigh-Mallory on the grounds that casualties would be prohibitive. He was overruled, however, by Eisenhower and supported in that decision by the key ground commanders, British general Bernard L. Montgomery and US general Omar Bradley.45
The counterair master plan for Allied air supremacy consisted of three main programs: continued policing to keep the Luftwaffe in a reduced state, strategic attack missions into the heart of Germany to keep German fighters tied down hundreds of miles from the invasion beaches, and wholesale attacks on airfields in France that the Luftwaffe could use to stage aircraft against the invasion.46
The constant pressure against the German Air Force was to be accomplished primarily through the aerial "guerrilla war" conducted by Eighth Air Force fighters. Ever since the decision in January 1944 to unleash the US fighters against those of the Luftwaffe "whenever and wherever they're found,"47 US fighter aircraft began to chase German aircraft down to treetop level and back to their bases.48 However, this change in strategy had a demoralizing effect on the bomber crews, who saw themselves as "bait" for the enemy fighters who would be left by their "Little Friends."49
The strategic bombings against Germany were continued until a week before the invasion, though some missions were diverted to specific preinvasion targets.50 On 25 March 1944, Eisenhower had decided in favor of the transportation plan over the oil plan.51 However, he did accede to Spaatz's desire to retain control over the heavy bombers until the last moment. Further, he informally allowed Spaatz to conduct some missions against oil targets.52
Spaatz fervently believed these attacks would destroy the Luftwaffe as an effective fighting force. By placing such high-value targets at risk, he was sure the Luftwaffe would be forced to defend them. He was further convinced that US fighter forces could take on the Luftwaffe anywhere, anytime and defeat them.53
The third part of the counterair campaign dealt with attacking the air bases in France. These largely unused airfields were considered a difficult target. First, any German fighters staging from them could rapidly shift to other locales before the attacks. Second, damage to runways could be quickly repaired. Furthermore, American experience in the Pacific had shown that aircraft had operated successfully off very difficult surfaces. Finally, just the sheer numbers of airfields--approximately 100 within 350 miles of Normandy--would strain the capacity of Allied air forces, even with the use of the heavy bombers of RAF Bomber Command and Eighth Air Force.54
The final part of the air campaign was the provision of an air umbrella over the invasion fleet and the landings themselves. Despite the success the Allies had achieved over the Luftwaffe, intelligence estimates prior to D day still placed enemy air strength at over 900 aircraft, including 450 bombers.55 Planners provided for a full complement of air cover. Eighth and Ninth Air Force P-38s maintained continuous cover over the invasion fleet. As forces moved ashore, the RAF furnished low cover while Ninth Fighter Command provided high cover.56 Eighth Air Force fighters conducted a sweep of the invasion area out to the periphery.57
Besides the attacks mentioned above, strategic forces in the months prior to the invasion continued to seek ways of getting the Luftwaffe airborne to fight. One of the most profitable proved to be attacks on Berlin. In many ways, this battle proved to be the "straw that broke the camel's back." German defenders pulled out all the stops, including recalling fighter units from the Eastern Front to repel the attacks. In a dramatic series of Allied raids in March 1944, the Luftwaffe was so drained that its leaders were forced to change tactics. Previously, while weather somewhat dictated response, they had attempted to oppose every raid. Now they realized that attacks on Berlin and Munich were being used to bait the Luftwaffe to fight. Therefore, they chose to become more selective in which raids they would counter. They attempted to catch the American forces off guard. Increasingly, they resorted to large mass attacks against the bomber streams--upwards of 300 heavily armed and armored "storm" fighters. The Allied fighters countered by attacking these "flying wedges" as they formed.58
The transportation plan singled out rail centers in Belgium and the northern region of the French rail system. These were selected for two reasons. First, chaos there would prevent the Germans from using their reserves, which were mainly in this area, to reinforce the invasion area. Second, coal for locomotives would be cut off from the rest of France, further inhibiting the movement of forces to Normandy.59
Initially, most of the attacks were carried out by the Ninth Air Force and the British Second Tactical Air Force. These started in early March 1944. The tactical air forces were used instead of the strategic forces for two reasons.
First, the British War Cabinet had reservations about the use of the heavy bombers. As mentioned earlier, there was great fear that many friendly civilian lives would be lost in such attacks on targets close to urban centers. The second reason was due to the continued disagreement RAF Bomber Command's Harris and the USSTAF's Spaatz had with Tedder and Leigh-Mallory over the efficacy of using the heavies to attack such precise targets. Thus, the heavies were slow to take up the transportation plan, necessitating the use of the tactical air forces.
To supplement the rail center strikes, the plan called for attacks directly against moving stock. Again there was concern over the potential loss of civilian lives. However, by mid-May 1944, attacks against moving trains were intensified. These were to be carried out primarily through fighter-bomber sweeps (the Chattanooga Choo-Choo missions) conducted by both AEAF and Eighth Air Force units. Planners saw a side benefit in these missions: they would sharpen the skills of the pilots in anticipation of ground support missions that they would be called upon to fly in support of the invasion forces.
The final assault by air power against the invasion beaches was to be a truly awesome display of might. RAF bombers plastered the beaches and coastal batteries in the early hours of D day followed by Eighth Air Force heavies at daybreak.60 Two major concerns were dealt with in these attacks. First, air planners expressed concern that such heavy saturation bombing would leave the beaches hopelessly cratered and would actually inhibit the movement of friendly invasion forces. To mitigate this problem, lightweight demolition and fragmentation bombs with instantaneous fuzes were used. The second concern dealt with the accuracy of the heavy bombers' delivery. Ground commanders wanted the heavies to attack within minutes of the forces hitting the beaches. Air planners were concerned, however, that this tight schedule could result in disaster if there was but a small error in delivery accuracy. Eisenhower made the final decision that called for the amphibious forces to land 10 minutes after the bombers' attack if skies were overcast and a scant five minutes if the bombers were able to attack visually.
After the beach attacks, heavy bombers returned to England to refuel and rearm for their second mission against towns and bridges inland from the beaches. These attacks were to slow any immediate German reinforcement. USSTAF commanders opposed these attacks on the grounds that they might needlessly kill thousands of civilians.61 They were overruled by Leigh-Mallory, who had assumed command of all the heavies on 1 June 1944.62
One of the most remarkable facts of the entire war is that the Luftwaffe did not make any significant daylight attacks on D day against Allied forces in the Channel or on the beaches.63 The Allies flew over 14,000 sorties in support of the landings alone while the Luftwaffe was only able to muster 319 sorties the entire day!64 This success is directly attributable to the length of the counterair campaign. The Luftwaffe had been finished. The remnants were tied to the defense of the Reich.
By late April 1944, it was apparent that much damage had been done to the rail centers. However, the system was proving much more resilient than planners had anticipated. The Germans had been able to repair bomb craters quickly and in some cases had been able to reroute rail traffic within a few hours. Moreover, the Allies had a difficult time assessing the effectiveness of the attacks.65 It was not due to a lack of intelligence data. Numerous photo reconnaissance missions and reports from occupied Europe showed great damage. But was physical damage an adequate measure of effectiveness? It appeared that there was a high degree of slack in the transportation system. Analysts concluded that the delays were being felt by the French and Belgian civilian traffic and not by the German military traffic.
The attacks against the moving stock were highly successful. They not only destroyed and disrupted enemy traffic but had a tremendous psychological impact on the train crews. French crews pressed into service by the Germans to operate the rail system deserted in large numbers, particularly when fighter-bomber pilots started the practice of dropping their nearly full belly tanks on the trains, then setting them afire through strafing attacks. The Germans were forced to replace the French train crews with their own troops, further reducing the capabilities of the German forces.66
Perhaps the most successful aspect of the preinvasion interdiction plan was the campaign against bridges. Those remaining were hit on D day. Ninth Air Force aircraft struck the Seine bridges while Eighth Air Force heavies attacked those over the Loire.67
Determining the efficacy of air attacks against the invasion sites is very difficult. First of all, little direct air support was requested.68 Second, postinvasion analysis found it extremely difficult to separate the damage done by naval bombardment and that done by air attack.69 Perhaps the best testimony comes from the success of the invasion itself. From 6 June on, German counterattacks, belatedly staged, were ineffective due to Allied air interdiction and close support.70
The lessons learned from Overlord planning are very applicable to the process of campaign planning today. First, the preinvasion planning was based upon sound principles of air warfare: (1) establish and maintain control of the air in the critical area for the purpose of eliminating the enemy's capacity to interfere from the air; (2) isolate the battlefield by interdicting enemy movements of troops and supplies; and (3) render immediate support to the ground forces on the battle front. The CBO accomplished the first task. The transportation plan (including the bridges part in that plan) accomplished the second. Finally, the combination of those two plans in decimating the Luftwaffe and rendering the German forces virtually immobile accomplished the third objective.
The second lesson learned is that integrated planning between air and ground forces works. This is not to say that such integration was voluntarily forthcoming and that it was always smooth and congenial. However, the fact remains that air planners consciously considered the requirements of the ground and naval forces in planning for Overlord. This was a reversal of previous invasions. During the planning for Operation Torch, air planners were ignored.71 During the planning for Operation Husky, air planners virtually ignored the ground invasion planners.72
The third lesson learned is a repeat of one that was painfully learned in North Africa: effective use of air power requires centralized command of air forces. Except at Eisenhower's level, and only after mid-April 1944, were all Allied air forces under one command. Why that occurred is outside the scope of this study, but any analysis must include aspects of bureaucratic politics, ideology, and personalities.
The fourth lesson was that a systematic and comprehensive air campaign planning process is a necessary but not a sufficient antecedent to successful air operations. Further, that such a process must start from an understanding of the objective to be attained and then proceed to the means of achievement. The end state was the surrender of Germany. The senior political leadership decided that the strategic air campaign and the invasion were the means to that end. The objective of the invasion planners was the successful lodgment on the Continent. One of the means they chose was the use of air power. Therefore, the objective of the air planners for the invasion was the efficient use of air power to achieve that end. By analyzing the enemy, they determined how best that goal could be accomplished. One can argue whether the transportation plan or the oil plan was best suited to achieve the invasion objective, but the fact remains that senior military leaders (i.e., Eisenhower and Tedder) chose the transportation plan because, in their judgment, it best fulfilled the objective for the invasion.
This leads to the final lesson learned: prudent planning requires a balance in targeting because of the uncertainty of war. The argument was not oil versus transportation. The plan was oil and transportation. The great British nineteenth century economist Alfred Marshall, when asked which was more important, supply or demand, reportedly replied that asking such a question is like trying to determine which blade of the scissors cuts the paper. It was in determining the balance between these opposing ideas that the argument lies. But referring to the above lesson, military planners must ask themselves, What is the objective I'm trying to accomplish? Spaatz played his role perfectly. He presented his case, and when he lost, he saluted smartly and carried out his mission to the best of his abilities.
The successful invasion of France is one of the most monumental military achievements ever recorded. The role that air power and air planners played in that success is perhaps best summed up by the words of the official Army Air Forces history of World War II:
So much of air's contribution to the success of the Normandy landings depended upon the cumulative effect of operations extending back through the days, months, and even years which preceded D day that D day itself, though providing an obvious climax to this preparatory work, seems almost an anticlimax.
There were no great air battles--so well had the preparatory work been done and so overwhelming were the Allied air forces that the Luftwaffe refused the challenge. The record of air operations in its most significant aspects points chiefly, therefore, to impressive evidence of a victory already won and to a massive effectiveness speaking first of the singularly undramatic skills of organization and planning.73
It is a lesson well worth remembering.
Notes
1. Due to the indecision of the German high command in issuing the orders, the Luftwaffe took the movement based upon its own authority. See Stephen L. McFarland and Wesley Phillips Newton, To Command the Sky: The Battle for Air Superiority Over Germany, 1942-1944 (Washington, D.C.: Smithsonian Institution Press, 1991), 242. McFarland and Newton translate Drohende Gefahr West as "Threatening Danger West." The author wishes to thank Dr Richard Muller of the USAF Air Command and Staff College for his more correct translation.
2. Ibid., 243.
3. Much of the debate over the Germans' lack of aggressive movement toward the landing beaches on D day concentrate on the egos of German general Erwin Rommel, who had responsibility for the Channel forces and Field Marshal Gerd von Rundstedt, commander in chief in the West. Liddell-Hart expresses the idea that the point is moot: "By smashing most of the bridges over the Seine on the east and over the Loire on the south, they [the Allies] turned the Normandy battle-zone into a strategic isolation-zone." B. H. Liddell Hart, History of the Second World War (New York: G. P. Putnam's, 1970), 547.
4. Readers interested in a deeper discussion of this model may examine the author's "Air Campaign Planning," Airpower Journal 7, no. 2 (Summer 1993): 11-23.
5. A note on usage. Throughout this study, I will use phraseology commonly used in the armed forces today. Planners in 1944 did not refer to "center of gravity" or other such phrases, though they did identify those concepts.
6. Pointblank was the code name for the Combined Bomber Offensive. See Col Ed Crowder, "POINTBLANK: A Study in Strategic and National Security Decision Making," Airpower Journal 6, no. 1 (Spring 1992): 55-65.
7. Crossbow was the code name for Allied air attacks against the German V-l and V-2 operations. It encompassed all phases of the German long-range weapons program. Started informally in late spring 1943, it was formalized in December 1943 and continued literally to the last days of the war in Europe. See Wesley Frank Craven and James Lea Cate, The Army Air Forces in World War II, vol. 3, Europe: ARGUMENT to V-E Day, January 1944 to May 1945 (Washington, D.C.: Office of Air Force History [New Imprint, 1983], originally published 1951 by the University of Chicago Press), 84-106.
8. Argument was the code name for Allied air operations specifically against the German aircraft industry. As such, it was designed to help achieve Pointblank's intermediate objective of destroying the German single-engine fighter force. It was the plan that became famous as "Big Week," 20-25 February 1944. See McFarland and Newton, 169-92.
9. Craven and Cate, vol. 3, 138.
10. Walt W. Rostow, Pre-Invasion Bombing Strategy: General Eisenhower's Decision of March 25, 1944 (Austin, Tex.: University of Texas Press, 1981), 6-7.
ll. War Department Field Manual (FM) 100-20, Command and Employment of Air Power, 21 July 1943.
12. McFarland and Newton, 2.
13. Ibid., 169.
l4. This command was established on 1 January 1944 to oversee administratively all US Army Air Forces in Great Britain (Eighth Air Force was commanded from 1 January 1944 by Maj Gen ("Jimmy") Doolittle and Ninth Air Force was commanded by Maj Gen Louis Brereton). It also conducted the strategic air campaign against Germany, controlling both Eighth Air Force in England and Fifteenth Air Force headquartered in Foggia, Italy.
l5. The command arrangements of the various air forces that took part in Overlord can be somewhat confusing, and they oftentimes caused a great deal of bitter debate. The issue (for the invasion) was resolved on 11 April 1944 when Eisenhower was given control over virtually all the air forces in Europe. He delegated to his deputy, Air Chief Marshal Tedder, responsibility for coordinating the air operations. USSTAF, AEAF, and RAF Bomber Command (under Air Chief Marshal Harris) were given equal stature. Air Chief Marshal Leigh-Mallory was officially designated air commander for Overlord and was given control of USSTAF and RAF Bomber Command's heavy bombers on 1 June 1944 for the invasion. See Craven and Cate, vol. 3, 80-81.
16. Ibid., 150.
17. Ibid., 157.
l8. This was the famous Operation Fortitude. It was no easy task. As Sir Michael Howard writes, "For the past six months [summer and fall of 1943] they [the deception planners] had been trying to persuade the Germans that they faced a major invasion threat from the United Kingdom [in order to tie up forces from reenforcing Mediterranean operations], when in fact they did not. Now they had to persuade them that they did not face such a threat whereas in fact they did." See his British Intelligence in the Second World War, vol. 5, Strategic Deception (New York: Cambridge University Press, 1990), especially chapter 6, 104.
l9. Craven and Cate, vol. 3, 168.
20. Ibid., 171.
2l. "General Eaker's Presentation of the Combined Bomber Offensive Plan to the Joint Chiefs of Staff," reprinted verbatim as the appendix in Barry D. Watts, The Foundations of US Air Doctrine: The Problem of Friction in War (Maxwell AFB, Ala.: Air University Press, 1984), 136.
He quotes from the Casablanca Directive, issued in January 1943.
22. Ibid.
23. The idea that strategic bombing would alleviate the need for an invasion was not a universal concept among all US air commanders. In his defense of daylight precision bombing at the Casablanca Conference, Gen Ira Eaker, commander of the Eighth Air Force, specifically couched his arguments in terms of preparing the way for the ground invasion. See James Parton, "Air Force Spoken Here": General Ira Eaker and the Command of the Air (Bethesda, Md.: Adler & Adler, 1986), 220-23.
24. DeWitt S. Copp, Forged in Fire: Strategy and Decisions in the Air War over Europe, 1940-45 (Garden City, N.Y.: Doubleday & Company, 1982), 381-84. See also Watts, 17-23; and David R. Mets, Master of Airpower: General Carl A. Spaatz (Novato, Calif.: Presidio Press, 1988), 200.
25. The historical debate over why the Americans and British believed the invasion was necessary is widespread. J. F. C. Fuller believes it was due to the "unconditional surrender" policy announced at Casablanca. See his A Military History of the Western World, vol. 3, From the Seven Days Battle, 1862, to the Battle of Leyte Gulf, 1944 (New York: Da Capo Press, 1956), 506-9. Another avenue suggests it was necessary to keep the Russians in the war. Whatever the reason, it had been agreed since the first US-British senior meetings in December 1941 that there would be an invasion of Europe. The arguments centered over where and when. See Gordon A. Harrison, "The Roots of Strategy," in Gordon A. Harrison, United States Army in World War II: The European Theater of Operations: Cross-Channel Attack (Washington, D.C.: The Office of the Chief of Military History, 1951), 1-45.
26. Supreme Headquarters, Allied Expeditionary Forces. This was General Eisenhower's headquarters, collocated with Spaatz's headquarters at Bushy Park, Teddington, on the outskirts of London.
27. See Alfred C. Mierzejewski, The Collapse of the German War Economy, 1944-1945 (Chapel Hill, N.C.: The University of North Carolina Press, 1988), 81.
28. Ibid., 82.
29. See Craven and Cate, vol. 3, 373-84. Operation Strangle was the air campaign designed to stem the flow of German supplies and reinforcements to the Italian front. It lasted from 19 March to 11 May 1944, when it was absorbed into Diadem, the campaign for the capture of Rome. Strangle grew out of earlier efforts by Mediterranean Allied Air Forces' attempts to cut enemy supply lines.
30. Mets, 200.
3l. Another major concern was the potential levels of civilian casualties. Since the rail centers were in and around large population centers, estimates of French and Belgian civilian casualties reached well over 100,000. See Mets, 210; and Craven and Cate, vol. 3, 79.
32. The issue came to a head at a 15 February 1944 meeting that included Tedder, Leigh-Mallory, Harris, Spaatz, Brig Gen Fred Anderson (USSTAF deputy commander for operations), Zuckerman, and their staffs. "Big Week" was still a week away.
33. Mierzejewski, 81.
34. McFarland and Newton, 229.
35. See Maj Gen Haywood S. Hansell, Jr., The Air Plan That Defeated Hitler (Atlanta, Ga.: Higgins-McArthur, 1972 [New Imprint, Air University, 1973]), 78-88. Interestingly, in AWPD-1, the German transportation system was ranked number two ahead of the oil system.
36. USSTAF estimated in early 1944 that only 14 plants produced 80 percent of the German synthetic petroleum supply, most of which went to gasoline. Spaatz argued that Germany could probably afford to lose 14 rail yards, but could ill afford to lose a like number of synthetic fuel plants. See Craven and Cate, vol. 3, 78.
37. Mets, 202.
38. Perhaps the most famous attack against oil refineries up until this time had been the 1 August 1943 attack by Ninth Air Force B-24s against Ploesti, Rumania. Of the 177 attacking heavies, 54 had been lost, most due to antiaircraft fire. While an estimated 42 percent of Ploesti's refinery capacity had been destroyed, the attack was not considered decisive. The Germans quickly repaired the damage and brought idle capacity at Ploesti on line. See Craven and Cate, vol. 2, Europe: TORCH to POINTBLANK, August 1942 to December 1942, 477-84.
39. It is interesting to note how senior ground commanders viewed this controversy. General Bradley, in command of all the US forces for the invasion, doubted whether air power could defeat Germany through oil attack nor did he have much confidence in their ability to defeat the Luftwaffe. He favored the transportation plan. See his A General's Life: An Autobiography of General of the Army Omar N. Bradley (New York: Simon and Shuster, 1983), especially 228-30. As Mets writes,
Spaatz argued that Leigh-Mallory's [transportation] plan was at loggerheads with his [Spaatz's] directives under the POINTBLANK plan, namely to defeat the Luftwaffe and gain air superiority before the landings. He insisted that the strategic air forces had to continue hitting vital targets in the interior of Germany to force the Luftwaffe to come up and fight so that it could be defeated before OVERLORD. Leigh-Mallory retorted that attacks on the rail yards in France would make the German fighters come aloft. Aside from the fact that such battles would not drive the Reich's surviving fighters back to their homeland and far away from the OVERLORD beaches, Spaatz asked his adversary what he thought would happen if the Luftwaffe chose not to come aloft. Leigh-Mallory answered that it would make no difference, for the great battle for air superiority would take place over the beaches on D day and the Allies would win it then. (Page 201)
40. Craven and Cate, vol. 3, 157.
41. Ibid., 373-84. Operation Strangle (see note 29) was conducted by the fighter-bombers of Twelfth Air Force's Air Support Command and the British Desert Air Force. It did not include Fifteenth Air Force's heavy bombers. Spaatz argued that the heavies, since they must attacked from higher altitudes, should not be used to attack bridges. Additionally, his experiments and those carried out by the RAF (using Typhoon fighter-bombers) showed highly promising results. Another interesting aspect of Strangle was its plan for "simultaneous interdiction" (page 374) on whole sections of the railways. Repudiating Zuckerman's concept of concentrating only on rail centers, Strangle's fighter-bombers attacked bridges, yards, tunnels, defiles, and open lines of track. Lt Gen Ira C. Eaker, commander of Mediterranean Allied Air Forces, concluded that the best means of interdiction was the destruction of bridges and viaducts. This was primarily due to the topography of Italy, where often bridges spanned deep gorges (and thus were difficult to repair and impossible to bypass), and the generally poor Italian road network.
42. General Montgomery's 21 Army Group, was given overall responsibility for planning the ground aspect of the invasion. Interestingly, 21 Army Group "had little faith in the efficacy of general attacks on rail centers." See Harrison, 228.
43. See note 31. The commander of the French forces in the United Kingdom, Gen Pierre Joseph Koening, when consulted on this issue, reportedly brusquely dismissed these concerns "with the comment that lives are lost in wars and that would be the price the French people would have to pay to escape their bondage." See Mets, 210.
44. Craven and Cate, vol. 3, 166-72.
45. Ibid., 70-71; and Harrison, 183-87. The choice of the landing sites was determined by the ground planners. US Army Chief of Staff Gen George C. Marshall thought the airborne assault plan too timid. He advocated a plan that called for a massive vertical envelopment to establish an airhead to threaten the Seine River crossings and Paris. This plan was developed by the chief of the US Army Air Force, Gen H. H. "Hap" Arnold.
46. Craven and Cate, vol. 3, 163.
47. Maj Gen Jimmy Doolittle, commander of the Eighth Air Force, considered the decision to remove the fighters from close escort of the bombers to actively seeking out the Luftwaffe was his most important decision of the war. See McFarland and Newton, 160.
48. Since the fighters were faster than the bombers, the escorts flew in waves. When the fighters, relieved of their escort duties and still with available ammunition, started their return flight, they dropped down to low level and shot up German bases, often catching German fighters as they were taking off or returning to land. See Mets, 197.
49. Similarly, it had a demoralizing effect on the German fighter pilots. In the opinion of the Luftwaffe's General der Fleiger Adolf Galland, once the US fighters were freed from the bombers, the Luftwaffe lost the war. In one memorable engagement, Galland found himself entangled with four P-51s. Though the Mustangs were themselves already 300 miles from home, they chased him at top speed and low level some 270 miles back towards Berlin. He escaped only through a ruse. See McFarland and Newton, 162-64; and Galland's The First and the Last (Mesa, Ariz.: Champlin Museum Press, 1986), 276.
50. The heavies sent 60 percent of their forces into the Reich on D-3 and D-2. The remainder attacked the Pas de Calais as part of the deception plan. See Craven and Cate, vol. 3, 143.
51. The supreme commander did not dismiss the potential effectiveness of the oil campaign. Rather, he decided that the transportation plan offered more immediate support to Overlord. See Mierzejewski, 84.
52. Eisenhower emphasized that these attacks were to test the theory that the Luftwaffe would fly to protect the oil fields. Missions flown in early May 1944 confirmed this. The Luftwaffe attacked in strength. Further, Ultra intercepts confirmed the effect on Germany. Antiaircraft defenses were redeployed to protect the plants. Furthermore, training programs for some ground units were curtailed. See Mets, 212.
53. Ibid., 205-7.
54. Craven and Cate, vol. 3, 163.
55. Ibid., 162.
56. It may seem odd that the longer-range P-38s covered the fleet while the shorter-range Spitfires covered the beaches, but this was done for sound reasons. It was believed that the distinctive shape of the P-38 would identify it as "friendly" to the greenest gunner in the fleet. See Mets, 214.
57. Craven and Cate, vol. 3, 189-90.
58. McFarland and Newton, 228, 235-36.
59. Craven and Cate, vol. 3, 150.
60. Not at all to be dismissed lightly was the airborne assault carried out by the paratroopers and gliders of the IX Troop Carrier Command. Two entire US divisions--the 101st Screaming Eagles and the 82d Airborne, totaling over 17,000 troops, were delivered in the early hours of 6 June 1944. See Craven and Cate, vol. 3, 186-88.
61. See Mets, 215. Spaatz was forced to instruct the bombardiers to withhold their release a few seconds to preclude any friendly losses. This caused many bombs to drop past the beaches and to be ineffective. According to Mets, ground commanders were disappointed with the invasion bombing.
62. Craven and Cate, vol. 3, 144-45.
63. Ibid., 166.
64. Mets, 214.
65. Mierzejewski claims that much of the difficulty can be traced to bureaucratic obstructionism. Because some organizations had been opposed to the transportation plan, they deliberately withheld information from analysts that may have shown its greater impact on the German economy than was initially believed. See Mierzejewski, 162.
66. Craven and Cate, vol. 3, 155-56.
67. Mets, 215.
68. The combined control center at Uxbridge received 13 requests during the day. Five were refused due to weather, lateness of the hour, or aircraft unavailability. This does not mean, however, that the tactical forces were not employed during the day. Both the Ninth and the Eighth Air Forces flew support missions throughout D day. They struck bridges, rail centers, conducted fighter sweeps, and strafed moving traffic (aided by the fact that the Germans had prohibited civilian traffic on the roads a few days prior) and choke points. See Craven and Cate, vol. 3, 193-95.
69. Ibid., 192.
70. Even the few instances of support to the D day operations proved decisive. On his discussion of the actions of the US V Corps, Harrison notes, "By dominating the battlefield, planes and naval guns smashed such German reserves as could be gathered for a counterthrust and so gave the fragmented V Corps infantry a chance to recover, rebuild, and again become a ground army superior in numbers and equipment to anything that the Germans could thereafter muster to meet them." Harrison, 326.
71. Torch was the invasion of North Africa by the US and British in November 1942. For the role that US Army Air Forces personnel played in planning that operation, see Richard G. Davis, Tempering the Blade: General Carl Spaatz and American Tactical Air Power in North Africa, November 8 1942-May 14, 1943 (Washington, D.C.: Office of Air Force History, 1989), especially 16-23.
72. Husky was the invasion of Sicily, which took place on 10 July 1943. For the coordination between air and ground planners, see Craven and Cate, vol. 2, 442-45.
73. Ibid., 185.
Lt Col Maris ("Buster") McCrabb (BA, Bowling Green State University; MS and MPA, Troy State University) is chief of the Warfare Studies Division at Air command and Staff College, Maxwell AFB, Alabama. Immediately preceding this assignment, he was department chairman of the Joint Doctrine Air Campaign Course of the Combat Employment Institute, Center for Aerospace Doctrine, Research, and Education (CADRE), Maxwell AFB. Colonel McCrabb is a command pilot with more than 3,200 flying hours in the F-4 and F-16 aircraft. During Operation Desert Storm, he was a member of the Combat Plans Division, Joint Task Force Proven Force, Incirlik, Turkey. Colonel McCrabb is a graduate of Squadron Officer School, Air command and Staff College, Air War College, and the US Army Command and General Staff College.
Disclaimer
The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.
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