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The Year Air Power Came of Age

By James S. Corum
8/7/2018 • MHQ Magazine

In 1917 over Flanders fields, a fundamental shift in the airplane’s role signaled its ascendancy as a deadly offensive weapon.

The air campaign over Flanders in 1917 represents a watershed in the development of air power. While aerial reconnaissance and observation had been widely employed from 1914 to 1916 and aviation technology had made enormous strides, air forces in the first half of World War I lacked a coherent doctrine and organization that tied together all the elements of air power to maximize its impact on the battlefield. In 1917 several factors came together that fundamentally changed the nature of aerial warfare. Both sides developed a comprehensive doctrine of air support, enabling airplanes to be employed in mass and with greater effect.

On the German side, major organizational reforms changed air support from being tactically useful to being an important operational force. Communications technology had developed to the point where fighter, reconnaissance, and anti-aircraft units could be effectively integrated and coordinated with the army. New technologies made it possible for air forces to conduct strategic bombing campaigns and to provide close air support on the battlefield.

The scope and scale of aerial warfare changed dramatically in 1917. Whereas air forces could field dozens of planes in the 1914- 1916 campaigns, both the British and Germans deployed hundreds of aircraft in 1917. The greatest aerial campaign of that year occurred over the Flanders region of northwestern France and Belgium. From June to November 1917, the Royal Flying Corps (RFC) with more than eight hundred aircraft confronted the German Imperial Air Service (or Luftstreitkräfte) with some six hundred aircraft in the skies over Flanders.

In many respects, the campaign represents the high-water mark for the Luftstreitkräfte in World War I. Outnumbered and often facing better-quality airplanes, the Germans more than held their own in the skies over Flanders because of their advantages in doctrine, training, and organization.

In late 1916, the Luftstreitkräfte was completely reorganized to reflect the importance of air power in all facets of combat operations. Authority over German air units in the first half of the war had been diffused among various army commands. The new organization placed all the aviation assets of the army under a single specialized headquarters and staff. Their assets included not only airplanes but also observation balloons, anti-aircraft units, support services, communications, and training units. The new structure established a single commander for the Luftstreitkräfte, the exceptionally capable General Ernst von Höppner, who answered directly to the high command.

Since air and ground campaigns had become very complex, Höppner and his staff devised an operational doctrine for coordinating large-scale air operations. In May 1917, the German air staff published a comprehensive manual for the Luftstreitkräfte that addressed such subjects as coordinated air defense and strategic bombing. Additional manuals provided detailed guidance for aerial reconnaissance and artillery spotting units and for employing air units to support ground attacks.

The new organization and doctrine was a decided improvement over the previous system in which the Luftstreitkräfte’s tactics and organization varied greatly from unit to unit. The new standardized concepts and procedures ensured that German air units could be quickly transferred between armies without having to undergo time-consuming retraining and reorientation.

Under the new organization, each field army had an aviation commander and staff coordinating all air and anti-aircraft artillery (Flug Abwehr Kanonen, or flak) units assigned to support that army. Although heavy bomber units came under direct control of the high command, some bomber wings were assigned to the army air groups.

The Luftstreitkräfte also established a forward observer corps, teams that monitored enemy air activity along the front lines. When enemy aircraft crossed the front, either to observe or attack German positions, the observer corps, tied into an extensive army aviation communications network, immediately reported the activity to the army aviation headquarters and the air defense command center. These command centers then notified the anti-aircraft units of enemy numbers, altitude, and direction. The army aviation commander could also notify his fighter units and attempt to intercept the enemy force.

Army aviation commanders maintained a special staff and communications net for the observation planes spotting for the army’s artillery. Other staff sections dealt with intelligence, aerial reconnaissance photography, and meteorology. An important new asset was a signals intelligence section that monitored enemy radio transmissions, broke their tactical codes, and analyzed enemy communications traffic. By the summer of 1916, the Luftstreitkräfte’s signals intelligence service could give specific warnings of impending Allied air operations through code-breaking and radio traffic analysis.

In 1917 Field Marshal Douglas Haig, commander of the British Expeditionary Force (BEF) in France, crafted a plan to break through the defenses on the German right flank in Flanders, on the northwest coast of France and southern Belgium. A breakthrough in Flanders seemed to promise a return to warfare in open country, where the Allied superiority in men and guns could be used to full advantage. An advance onto the Flanders plain would also allow the British to pierce the German transportation and logistics network. Haig believed that German morale was low, and he thought that making such a major breakthrough and disrupting the enemy’s support systems would deal a decisive blow to the German army.

In fact, German morale remained high. Recognizing the numerical inferiority of their army, the Germans had adopted a defensive strategy on the Western Front in early 1917 that forced the Allies to accept heavy casualties for minor gains on the ground.

Along most of the Western Front in early 1917, the Germans withdrew to the Hindenburg Line. By strategically giving up ground, they straightened and shortened their front, pulling back to carefully prepared defensive positions. In April 1917, the new strategy proved effective when a major French offensive under General Robert Nivelle shattered against the new German defensive lines. Nivelle’s forces suffered such horrendous casualties that many of the French divisions mutinied.

In Flanders the Germans had no option to trade space for better defensive positions. The major German submarine bases were located on the Channel coast, close behind the front lines in Flanders. They were essential to the high command’s program of unrestricted submarine warfare. The air bases where the Germans were assembling a force of heavy bombers to attack England were also in Flanders. If the Flanders front broke, these air and U-boat bases so important to German strategy would be overrun. In this sector, retreat was not an option.

The main British problem was that Flanders had bad terrain for waging a land war. A few ridgelines dominate the easily flooded lowlands—and the ridgelines were mostly in German hands. The British First and Fifth armies would have to take the high ground along those ridgelines before they could drive across the open Flanders plain. Any British offensive would require a series of frontal assaults against carefully prepared German defenses.

Opening with an attack on Messines Ridge on June 7, 1917, Haig’s Flanders campaign consisted of a series of major British thrusts designed to overrun the high ground around Ypres and Passchendaele and break through to the Flanders plain. For five months after the June 7 attack, both armies suffered horrendous losses on a battlefield not much larger than the island of Manhattan.

German and British memoirs recall the fighting as some of the most vicious and intense of the war, and the heavy rains and poor drainage of the region increased the soldiers’ misery. Rain turned the ground into a morass. Trenches and dugouts flooded, and hundreds of wounded soldiers drowned. Moving artillery and supplies forward through the pervasive mud required extraordinary efforts.

After the first stage of the offensive at Messines, the Germans reinforced the Flanders sector so that the second phase of the British attack, which started on July 31, failed to achieve the expected breakthrough. In August and September, Haig’s hopes for a rapid transition to open warfare were dashed, and the campaign became one of attrition. With superior numbers, the British hoped to overwhelm the enemy on the ground, inflict heavy losses, and cripple the German army.

The concept of attrition warfare was considered equally valid for the air campaign. The plan for the Royal Flying Corps, commanded in France by Maj. Gen. Hugh Trenchard, was one of relentless offensive operations over the German lines. With their superior numbers, the British expected to blast the Germans out of the skies and ensure that British observation and reconnaissance aircraft could support the ground troops relatively unmolested. By controlling the skies, they also intended to deny the Germans the ability to fly their own reconnaissance and observation missions.

The British strategy required many airplanes and anticipated heavy losses. They had a clear superiority in men and material throughout the battle, however, and expected to maintain that superiority as the British aircraft industry reached full production levels. The RFC and the Royal Naval Air Service (RNAS), supported by some Belgian and French air units, began the campaign in June with 748 aircraft opposing three hundred German planes under command of the Fourth Army, which covered the Flanders front.

When the British attacked at Messines, the Germans recognized the danger that a breakthrough posed and rushed ground and air reinforcements to Flanders. By July the Allies had approximately 840 airplanes opposing six hundred German planes in Flanders. Trenchard wanted to win air superiority by deploying superior numbers of fighter aircraft, so by July the British had twenty-nine fighter squadrons in Flanders with three hundred fifty fighters against two hundred German fighters. From June to November 1917, both the British and German air forces focused mainly on the Flanders front.

Captain Helmuth Wilberg, a general staff officer and one of Germany’s most experienced aviators (he held imperial pilot’s license number twenty-six), commanded the Luftstreitkräfte units in Flanders. Wilberg had served on the army’s air staff, commanding air units on the Eastern Front in the first half of the war, and Höppner regarded him as an exceptionally competent commander.

Wilberg’s forces fought on the defensive, and this gave them several advantages. To win air superiority, the British had to cross the lines. Most aerial combat was over the German side of the front. This meant that if a German aircraft was damaged, the pilot could break off combat, land at a nearby German airfield, and survive to fight again. Because prevailing winds in Flanders blow from west to east, German aircraft damaged over British lines could often glide to a landing on their own side. Those conditions saved Manfred Freiherr von Richthofen from capture when he was wounded in a dogfight on July 7, 1917. Germany’s top fighter commander managed to glide in for a rough landing behind his own lines. He returned to combat in August.

If a British aircraft was damaged over German territory, the pilot had to fight the wind to return to his home base. British airmen thus faced a far greater risk of capture if their planes suffered serious damage or ran low on fuel.

A defensive strategy also allowed the Germans to use their superior antiaircraft defenses to advantage. Throughout the war, the Germans put more emphasis on developing anti-aircraft artillery than the Allies. By 1917, this began to pay off. Flak in 1914- 1916 had consisted mostly of modified artillery pieces. Given the guns’ low velocity and primitive range-finding systems, they were not very lethal.

In 1917, however, new, specially designed high-velocity guns that could hurl an explosive shell to high altitude appeared. The new guns, coupled with fire control directors (early mechanical computers), greatly increased flak’s lethality. German flak shot down 467 Allied planes in 1917 and more than seven hundred in 1918.

As the Flanders campaign began, the Germans deployed seven flak groups with 252 guns and twenty-eight searchlights to that sector—a considerable force by World War I standards. The British had less interest in anti-aircraft guns and deployed far fewer of them. Moreover, British anti-aircraft guns were much less effective than German guns.

Artillery was the most lethal killer of World War I. Success in any major operation in 1917 depended on effective fire support. Artillery dominance was necessary to first smother the enemy defenders during the initial advance. Its mission then was to enable the attacking infantry to hold newly won ground by breaking up any enemy concentrations preparing to counterattack.

If artillery dominance was the key to victory, then the airplane was the key to maximizing artillery effectiveness. The moment of greatest vulnerability for the World War I infantryman came when ground units concentrated, either for the attack or counterattack. Ernst Jünger’s classic book of World War I combat, Storm of Steel, vividly describes several occasions when whole companies were wiped out by a few well-placed artillery rounds hitting units massed for attack. Sometimes this was due to luck or a carefully plotted artillery firing plan. In many cases, however, it was achieved with the assistance of well-trained aerial observers who were able to spot targets such as troop concentrations and direct immediate and accurate fire upon them.

Supporting the artillery was by far the most important tactical mission of World War I air forces. Aircraft conducted aerial surveillance, mapped out enemy positions, and identified targets on the front line and behind the lines so that the artillery could accurately strike those targets.

The air forces of both sides were processing tens of thousands of aerial photographs per month by 1917. When major ground battles erupted, aircraft identified targets for the artillery—enemy artillery positions as well as enemy troop movements.

By 1917 aerial observation had become a highly specialized art. During the Flanders campaign, the RFC and the Luftstreitkräfte normally assigned at least one squadron of two-seater observation planes to support the artillery of each army corps. Both sides created new doctrines to increase the effectiveness of aerial spotting.

Before 1917 RFC observers had to work out their own signaling and spotting procedures with each artillery unit they supported. Variations between units meant that whenever observation squadrons were shifted to support a new corps, they had to learn a new spotting system. To correct that problem, in mid-1917 the RFC and the ground forces standardized signal and observation procedures. This reduced confusion and enabled any observation squadron to be shifted to support a new army corps or a new sector of the front without time-consuming coordination.

The Luftstreitkräfte took the development of artillery observation procedures to a higher level by introducing radio communication—pioneered by the British—to frontline operations on a regular basis. Early in the war, radios had been too heavy to install in anything but Zeppelin airships or heavy bombers. By 1917, however, German industry was producing radios small and rugged enough to easily mount in the reconnaissance planes operating over the front lines. The new German doctrine established a standard system of formal radio nets and simple codes for artillery observers.

In Flanders Captain Wilberg had the region mapped into specially coded grid squares. German observers in the air, using radios, could tell the artillery headquarters the nature of the target and its exact location simply by tapping out a few letters in Morse code. Adjusting fire in the course of battle became much simpler and more efficient—hence more deadly.

Observers in kite balloons tethered behind the front also played an important role in World War I fire control. Both sides stationed balloons at intervals every few miles along the front. Their cables allowed an observation altitude of forty-five hundred feet. At that height, the soldier in the basket could observe activity on the front and several miles behind, and telephone reports to the artillery command center. By 1918 the Germans alone operated five hundred balloons at the front.

Since knocking down the enemy’s balloons helped blind his artillery, balloon busting was an important task. Shooting down a big stationary target filled with explosive hydrogen gas may sound simple, but the average flier dreaded the job. Because balloons were obvious targets, the Germans surrounded theirs with flak batteries, including the newly developed and very deadly rapid-firing 37mm anti-aircraft guns. Balloon attackers as a result suffered high casualties.

Then as now, the primary fighter plane mission was to win air superiority. Fighters worked to ensure that their side’s artillery spotters and reconnaissance planes could do their job effectively. At the same time, they sought to deny the enemy’s reconnaissance planes, artillery spotters, and bombers access to the sky over and behind their own forces.

A major German organizational step came in June 1917 when four fighter squadrons, or Jagdstaffeln (Jastas 4, 6, 10, and 11), were organized into Fighter Wing 1 (Jagdgeschwader I, or JG I) under the command of the celebrated “Red Baron,” Richthofen. The new organization fielded more than fifty aircraft that could fly and fight as a single unit.

By the summer of 1917, the day of the lone ace seeking knightly aerial combat at dawn was over. Massed fighter engagements became the norm, and new tactics and formations stressed employing several squadrons at once. Through the summer and fall of 1917, the British would commonly fly two to four squadrons over the German lines and face an equal number of enemy aircraft.

Because the Germans had an efficient warning and communications system, they could choose the time and place to engage enemy fighters. Captain William Avery Bishop, Canada’s top ace, described the German approach to fighter combat: “Almost every evening we would find well-laid traps set for us….Four or five Huns would come along and we would engage them. Then suddenly as many as fifteen or twenty would appear from all angles and join in the fight.”

The Germans would meet the British incursions over their lines by putting up one squadron at fourteen to fifteen thousand feet to dive on the enemy, arranging for another squadron or two to intercept at eight to ten thousand feet, and keeping a squadron to the flank or rear, ready to intervene and cut off British stragglers. The new wing organization and tactics proved highly effective in combat. Throughout the latter half of 1917, the Luftstreitkräfte reorganized other fighter squadrons into temporary groupings called Jagdgruppen.

Once battle was joined, the careful wing and squadron formations fell apart and aerial combat became a huge melee of individual dogfights. Piloting skill, good shooting, and a lot of luck were the keys to survival. Cecil Lewis, a British fighter ace with the RFC’s famed No. 56 Squadron, described a few seconds of a typical large dogfight: “A pilot, in the second between his own engagements, might see a Hun diving vertically, an S.E.5 on his tail, on the tail of the S.E. another Hun, and above him another British scout. These four, plunging headlong at two hundred miles an hour, guns crackling, tracers streaming, suddenly break up.”

The British aircraft industry was now producing large numbers of fighters, enough to reequip many of the RFC fighter squadrons with new aircraft for the Flanders campaign. The highly maneuverable Sopwith Camel and the sturdy and fast S.E.5a were among the top planes introduced over Flanders. The Bristol F.2B, a superb two-seat fighter, had also entered service, and several of the British squadrons flew Bristols.

The French also supplied the RFC with some Spad VIIs, exceptionally fast and rugged planes. The British were determined not to repeat the disastrous battle of Arras in “Bloody April” 1917, when the RFC’s fighter force, equipped with predominantly obsolete aircraft, faced superior German planes and lost 151 aircraft to Germany’s sixty-six.

The quality of the new British fighters dismayed German air commanders. Richthofen wrote to an officer of the Luftstreitkräfte staff on July 18: “Our airplanes are inferior to the English in a downright ridiculous manner. The [Sopwith] Triplane and the two-hundred-horsepower Spad, like the Sopwith single-seater [Camel] play with our [Albatros] D-5s. Besides better quality aircraft they have quantity….the D-5 is so antiquated and laughably inferior that we can do nothing about it.”

Fighter pilots characteristically exaggerate the capabilities of enemy aircraft, however, and it is impossible to assess the relative advantages of German and Allied fighters in 1917 from pilot testimony alone. For example, one can contrast Richthofen’s pessimistic assessment of his fighters with the opinion expressed by Cecil Lewis of his own new fighter against the Germans over Flanders: “Unfortunately, it soon became clear that, as good as the S.E.5 was, it was still not equal to the enemy. Scrapping at high altitude, fifteen to eighteen thousand feet, the Huns had a marked superiority in performance. This naturally tended to make us cautious, since we knew that, once we came down to their level, we should not be able to get above them again.” The Royal Aircraft Factory addressed this complaint with the S.E.5a, slightly redesigned and sporting a 200-hp engine in place of the S.E.5’s 150-hp Hispano-Suiza.

While air power historians rate the newer Allied fighters of 1917 such as the Spad VII, the S.E.5a, and the Sopwith Camel as having a performance edge over the German Albatros D.IIIs and D.Vs, and Pfalz D.IIIs in mid-1917, the relative advantages were slight. Indeed, the twenty-nine fighter squadrons of the RFC and RNAS in Flanders were equipped with thirteen different aircraft types. Many Allied fighter units over Flanders still flew obsolete aircraft such as the de Havilland D.H.5, the Sopwith 11⁄2 Strutter, and the F.E.2d. These models were clearly inferior to the German fighters and provided easy opportunities for German aces.

Pilot training was the biggest difference between the Allied and German fighter forces. From the very beginning of the war, German pilot training was far more thorough and systematic than British training.

German pilots went through a basic course of sixty-five flight hours before they were assigned to an air unit at the front. In 1916, when fighter aviation evolved into a highly specialized branch of aerial warfare, the Germans set up a special fighter training center in Valenciennes, France. In three- and four-week courses, new pilots detailed to fighter units learned tactics from veteran pilots with experience at the front.

In contrast, RFC pilot training was informal and haphazard. Indeed, training accidents caused the greatest number of deaths for British airmen in World War I. A total of eight thousand airmen were killed while training in the United Kingdom—a record of casualties per training hours that far exceeded the German, French, and American numbers.

John Slessor, later a marshal of the Royal Air Force, recalled that he flew his first combat mission in late 1915 straight out of pilot training, when he had a total of thirty-five hours’ flying time. Earlier in 1917, during the Arras offensive, the RFC threw pilots into the battle who had only fifteen hours’ total flying time. In the summer of 1917, the RFC was finally addressing the training problem, and top fighter pilots such as Captain James T.B. McCudden were periodically taken out of combat and sent to operational squadrons to teach fighter tactics.

In the skies over Flanders in the summer of 1917, however, the German advantage in training paid off handsomely. Between June and October 1917, the British lost more than nine hundred airmen killed over Flanders versus approximately three hundred German losses.

In late August, the debut of the Fokker F.I triplane boosted German fighter pilot morale. The British had equipped some squadrons with Sopwith Triplanes in the spring of 1917, and the Germans found them to be dangerous opponents. One Triplane captured in April 1917 was sent to Berlin for analysis. Aircraft designer Anthony Fokker, at the high command’s urging, reluctantly created a German version of the plane, but he used an innovative cantilever wing structure that did away with the wire bracing characteristic of the Sopwith Triplane and biplanes of the time.

The first two preproduction triplanes, designated F.Is, were sent to Richthofen’s JG. I in Flanders. The plane’s outstanding maneuverability and responsiveness delighted the German pilots. They also came as a surprise to the British, who lost several observation aircraft over the front because British pilots mistook approaching Fokkers for friendly Sopwiths.

Soon, however, the Germans discovered that the new triplane, redesignated Dr.I for dreidecker (triplane), had major defects due to poor quality control—never a strong point in the Fokker aircraft factory. The top wing structure of some of the early Dr.I production models sometimes collapsed during strenuous aerial maneuvers. Two German pilots were killed in accidents in October 1917, and the new Fokkers were all grounded for several weeks while modifications were made. Meanwhile the Jagdstaffeln soldiered on through the Flanders campaign with their Albatros and Pfalz scouts.

In 1917 the role of the air arm shifted, with more emphasis placed on offensive operations. Increasingly, aircraft were used to attack troops on the ground and tactical targets behind the front such as artillery positions, supply depots, and troop concentrations. Trenchard now gave his fighter squadrons general orders to fly into enemy territory and seek targets of opportunity, including German gun emplacements and supply trains. To support the attack at Messines in June, Trenchard ordered his fighters to “cross the line at Armentieres very low and then shoot at everything….”

Such tactics occasionally resulted in serious damage to the Germans, but more often the British suffered heavy losses from groundfire with little to show for their efforts. British flight commander Arthur Gould Lee of No. 46 Squadron regarded such missions as “a wasteful employment of highly trained pilots and expensive aeroplanes….I would much prefer to go through half a dozen dogfights with Albatrosses.”

Helmuth Wilberg chose a very different approach to ground attack. He took the Schutzstaffeln, German two-seat fighter units originally created to escort observation planes, and reorganized them into attack groups (Schlachtgruppen), each with three Schlachtstaffeln (or Schlastas) of six planes. These attack groups were then trained and equipped for low-level strafing and bombing operations.

The German two-seat fighters such as the Hannover CL.III and the Halberstadt CL.II were well suited to their new role. They were fast, compact, and rugged and armed with one or two forward-firing machine guns and one machine gun in the rear cockpit that the observer fired. The observer could also drop four or five twenty-two-pound bombs. For maximum effect, Wilberg decided to use his specially trained attack groups only in massed assaults. He deployed the new groups to support German counterattacks or intervene in a defensive battle, to slow enemy breakthroughs.

Wilberg also took the initiative to mount radios in the ground attack aircraft, and with this radio network directed the squadrons onto targets. Thanks to his control network, German attack groups responded quickly and helped slow the British advance at Messines Ridge on June 6-14.

One of the most dramatic applications of air power in the campaign occurred on September 6, 1917, as the British advanced over the Somme River bridges at Bray. German aerial reconnaissance spotted the concentration of British reserves at this chokepoint, and 24 Halberstadts dived into an attack just as the British were crossing the bridges—their moment of greatest vulnerability.

British troops jammed on the narrow approach ran in every direction to evade the relentless machine-gunning and bombing. The Halberstadts also attacked British artillery units farther in the rear. One British division was completely disorganized, and the British advance was checked without German losses.

The success of such ground attack operations encouraged the German air staff to increase the size of the specialist force and to push development of aircraft designed for close air support. Late 1917 and early 1918 saw a major increase in the size of the German ground attack force plus new equipment such as an improved version of the Hannover, the CL.IIIa.

Signaling a major step forward in German aircraft design, in late 1917 some ground attack units were reequipped with the new Junkers J.1, an all-metal sesquiplane specially built for close support missions. With its armor protection for the engine and aircrew, the Junkers was virtually invulnerable to groundfire. The J.1 and other ground attack planes played a major role in supporting the successful German counterattack at Cambrai in December 1917.

In addition to enhancing ground attack capabilities, the German high command also put a high priority on developing heavy bombers that could reach targets deep behind enemy lines. By early 1917, the German aviation industry had developed several heavy bomber models.

The Gotha G.IV, which arrived in early 1917 and became a standard bomber on the Western Front, was powered by two 260-hp engines and carried an eleven-hundred-pound bombload. The Luftstreitkräfte planned to build a strategic bomber force of 108 planes by the spring of 1917. First priority was readying a wing of forty G.IVs, known as the “England Wing” (Englandgeschwader), for an air campaign against London.

The high command also recognized the utility of heavy bombers interdicting and disrupting enemy logistics far behind the front. As the Flanders campaign began, the Germans transferred two heavy bomber wings to support the Fourth Army and carry out strategic interdiction against the BEF’s ports and major supply depots. Because the high command viewed Flanders as a critical front, the air staff also granted Captain Wilberg the authority to call on the bombers of the England Wing to attack BEF logistics in France.

Other German bomber units were ordered to attack French rail lines and disrupt Allied rail traffic to Flanders, giving priority to targets that were likely to cause the most damage and create bottlenecks in enemy transportation. The primary targets were field depots, rear area rail switchyards, headquarters, communications centers, ammunition dumps, and industrial facilities producing war material.

The Germans preferred mass attacks to inflict maximum damage. Recognizing that Allied defenses were likely to make daylight bombing raids too costly, they opted for night attacks. At night, enemy anti-aircraft fire would be ineffective and the bombers were unlikely to encounter fighters. This allowed them to fly lower. That, in turn, allowed the night raiders to carry heavier bombloads.

Nocturnal air operations, however, presented German airmen with a new range of problems that required new technological solutions. Navigating at night was difficult. As the war progressed, the Germans established an aerial “lighthouse” system in which high towers would emit unique light signals, usually a Morse code sequence, visible to the bombers.

In addition to lighthouses, various lights in the shape of crosses, triangles, etc. were set up behind the front to help steer the bombers to their objectives. In good visibility, such signals could be seen for forty miles. Another ingenious night navigation method was for anti-aircraft guns to fire parachute shells of different colors at an altitude of six thousand feet. Such shells could be sequenced or color-coded and were visible from thirty to sixty miles.

The Germans also developed highly effective systems for night landings, with sunken lamps set into the middle of landing fields acting as beacons. A series of red lamps radiating out from the central beacon gave the wind direction, so that the pilot could land into the wind. Electric lamps were also used to illuminate the airfields. The Allied air forces were far behind the Germans in night flying and had no comparable systems.

For success, bombers depended heavily on accurate intelligence. The standard German two-seat reconnaissance planes (the largest segment of German air power at the front) faced high risks to obtain intelligence, even when flying short distances over the front lines to take aerial photos. Normally, several fighters escorted such recon flights. Bombing targets deep behind enemy lines, however, was another matter. It required long-distance photoreconnaissance missions that involved flying for hours through skies protected by enemy anti-aircraft defenses and fighters.

Had the Germans used regular reconnaissance aircraft for long-range flights, they would have required a strong escort force for every mission—and even then the chances of success would have been low. So the Luftstreitkräfte found a solution in altitude—they simply flew high above the enemy defenses, in special planes.

One such craft was the Rumpler two-seat C.IV, introduced in 1917 and specially designed for high-altitude, long-range reconnaissance. With a large, efficient wing designed for maximum climb and altitude performance, the C.IV could take its pilot and observer, both equipped with oxygen, up to twenty thousand feet to photograph enemy targets with their excellent Zeiss cameras. The Germans also developed electrically heated flight suits that allowed extended operations in the extreme cold of high altitudes.

Later in 1917, Rumpler fitted a high-compression 240-hp Maybach engine to a modified C.IV, and this became the C.VII. The new engine gave the C.VII a ceiling of approximately twenty-four thousand feet. At twenty thousand feet it could maintain a speed of one hundred mph—incredible performance for a 1917 airplane.

No Allied fighters could fly as high as the Rumpler, nor could anti-aircraft guns reach it. With the Rumpler, the Germans could photograph targets deep within France in relative safety—as they flew two thousand feet above the ceiling of most Allied fighters.

British ace James McCudden was one of the very few Allied pilots who managed to bring down a Rumpler. McCudden, an RFC mechanic before he became a pilot, specially modified his S.E.5a for high-altitude flight. Yet even a superb pilot like McCudden only managed to bag such high-speed, high-altitude reconnaissance planes as the C.VII on relatively few occasions—and then it was generally because the Germans made mistakes. On one occasion McCudden got lucky when a German pilot turned his plane to give the observer a good shot at the enemy and lost altitude, bringing his Rumpler down to where McCudden could hit him. In another instance he tried to shoot a Rumpler at eighteen thousand feet, but the German pilot kept his height advantage and returned safely to his lines.

Armed with good intelligence provided by his long-range reconnaissance planes, Captain Wilberg used his two heavy bomber wings to conduct a series of raids against British and French airfields and air depots, as part of an air superiority campaign. To minimize the danger from British fighters and anti-aircraft guns, German bombers attacked at night, dropping parachute flares to illuminate their targets.

Several German raids on the Allied airfields were very successful. One strike against the British airfield at Bray Dunes on the night of July 6, 1917, damaged twelve aircraft. On September 24, German bombers attacked the British airfield and depot at St. Pol-sur-Mer and heavily damaged the base. One bomb hit a hangar and destroyed one hundred forty stored aircraft engines, most of the RFC’s replacement power plants in Flanders. In October the German bombers returned to St. Pol and destroyed thirty-six British and French aircraft, severely damaging the hangars and depot. Those raids destroyed a large number of Allied aircraft on the ground and inflicted heavy damage, with little loss to the Germans.

During the height of the Flanders battle, the Germans conducted numerous bombing raids against the French rail yards supporting the BEF’s offensive. BEF port facilities in northern France, especially at Calais and Dunkirk, also came under attack. The Germans tried to disrupt the British logistics system with a series of night raids that began in June 1917, and several raids were highly successful. In August the British ammunition dumps at Dunkirk were badly damaged, and after one especially devastating raid on Dunkirk on October 3 it took four days to put out the fires.

Captain Alfred Keller, a specialist in night bombing, was awarded the Orden Pour le Mérìte after his wing dropped one hundred thousand kilograms of bombs on Dunkirk. During the Flanders campaign, German heavy bombers dropped a total of three hundred thousand kilograms of bombs on BEF rear areas.

While German bombing failed to seriously disrupt British logistics, it caused considerable concern. General Höppner could reasonably claim that his bombers had inflicted significant damage upon the enemy.

After five months of combat on the ground and in the air, the Flanders campaign was essentially a draw. The British advanced their lines by nine thousand yards at a cost of more than four hundred thousand casualties. The Germans suffered two hundred seventy thousand casualties in the same period. The British came close to breaking the final German defensive lines and advancing to the Flanders plain, but they failed before the onset of winter ended the battle.

In the final reckoning, the RFC managed to carry out its mission. Thanks to fighter cover, the British observation and artillery spotting planes did their jobs quite effectively. British artillery was accurate and intense, and accounted for the heavy German losses, but it all came at a tremendous cost to the RFC.

Trenchard used his greatly superior numbers of fighters aggressively—but not very cleverly. RFC aircrew losses were three times those of the Germans (nine hundred dead versus three hundred). Superior German training and tactics, as well as a good communications system, more than overcame British advantages in aircraft quantity and quality. Some credit must also be given to the superior German flak force, which accounted for about twenty percent of all British aircraft losses.

Despite the daunting numbers they faced, the German airmen were also able to do their job. The Luftstreitkräfte—especially the artillery spotters and ground attack units and the fighters that covered them—deserves considerable credit for effectively supporting the German counterattacks and keeping the British from making a decisive breakthrough. While both sides bombed the other’s airfields and logistics, German attacks were more effective. The Germans dropped more bombs behind enemy lines than the British and inflicted considerably more damage. German close air support tactics had much greater effect on the battlefield and with far lower losses.

In short, big battalions are useful but don’t always win. While both sides made significant strides in organization, technology, and tactics, the Germans generally fought the smarter war. Superior organization, doctrine, and tactics made the difference, enabling the Germans to hold their own in the air in 1917.

 

Originally published in the Winter 2008 issue of Military History Quarterly. To subscribe, click here

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