Operation Crossbow Part I

Interdiction and Crossbow

On Sunday morning, June 18, 1944, Clementine Churchill, the prime minister’s wife, visited London’s Hyde Park to see her daughter Mary, who was a young officer serving with the local anti-aircraft battery. It had been a busy week on the home front. Almost two weeks prior, the invasion force had departed British ports and landed on the Norman coast. Early optimism over the landing’s success had receded slightly as the Germans had launched a new aerial assault, this time with unmanned, pilotless bombs. Mrs. Churchill arrived while the guns were firing at one of these strange contraptions, which sounded like a truck struggling, with its engine sputtering, to climb a steep hill. This particular aircraft passed overhead unharmed and destroyed a nearby house. As the mother and daughter were talking, another bomb appeared in the sky, and the battery again fired frantically at this machine as it flew overhead. Not hit, its engine stopped as scheduled, dove to earth, and exploded beyond the view of the women. Mrs. Churchill did not realize until later that morning that the explosion took place at the Guards Chapel at Wellington Barracks near Buckingham Palace. A service was in progress, and the bomb killed or wounded more than two hundred active and retired members of the brigade. This incident was the most destructive V-1 attack of the war.

The German flying bomb and rocket offensive came as no surprise to Allied leaders. Although the first attack did not take place until the middle of June 1944, British intelligence had known about German research in this area since 1939. Throughout 1942 and 1943, evidence continued to accumulate that this research had progressed beyond the simple experimentation stage. For several years, German scientists had been laboring at several locations, especially Peenemünde on the Baltic Sea, to perfect these systems to strike at the English enemy. By early 1943 it became apparent to British intelligence specialists that these programs were potentially dangerous and that the government needed to take action. It was ironic that this news arrived just as the prospects for Allied success in the war against Nazi Germany were improving. America had been in the conflict for more than a year, and its forces were now fighting the German army in North Africa. Its buildup of troops in the British Isles continued, and the US Eighth Air Force had joined RAF Bomber Command in its campaign against German industry. The Soviet Red Army had thrown back the Nazi offensive at Stalingrad and appeared to have turned the tide in the east. But it was premature to celebrate as new weapons emerged that seemed to threaten the foundation of the Anglo-American war effort. From the week after D-Day in June 1944 until the end of the war, British civilians lived under the constant bombardment of Hitler’s so-called vengeance weapons (Vergeltungswaffe). Most students of the Second World War are aware that the V-1 pilotless bomb and the V-2 rocket wreaked havoc on London, eastern England, and Antwerp until March 1945, when Allied forces overran the last launcher units. When it was over, the V-weapons had killed approximately 9,000 British and 1,400 Belgian civilians and wounded more than twice that many.

This shooting war, however, began almost a year earlier, under Operation Crossbow. From June 1943 until the end of the war, Allied heavy bombers attacked Peenemünde and other construction and testing facilities in Germany. These attacks fit into the already established parameters of the Combined Bomber Offensive, so there was no actual diversion of effort. What was a controversial deviation from the strategic forces’ intended role, however, was their large-scale employment to attack these systems and their facilities in France. Crossbow was a massive effort that from August 1943 until August 1944 consumed more than 15 percent of the total tonnage dropped by the RAF Bomber Command and the US Eighth Air Force. This operation also drained the resources of the two tactical air forces, the US Ninth Air Force and RAF Second Tactical Air Forces, as medium bombers and fighter-bombers attacked suspected V-weapon facilities. So important was it to the Combined Chiefs of Staff to find these launchers that from May 1943 until April 1945 it dispatched more than four thousand reconnaissance sorties in search of these weapons, more than 40 percent of the total. Across northwestern France, most of these attacks, often with more than fifty bombers at a time, took place near the small villages that dot the departments of Pas-de-Calais, Somme, and Nord. Few remember these events. Unlike the bombing of Rouen, Le Havre, Caen, and Saint-Lô, whose citizens have commemorated the Allied destruction of their cities, there are few memorials to the French citizens of this region. The number of casualties caused by this and related bombing efforts is not insignificant. Although exact losses are always difficult to estimate, Allied air attacks collectively killed approximately 8,460 civilians in the departments of the Pas-de-Calais, the Nord, and the Somme. If just 10 percent of those were as a result of the Noball offensive, which is reasonable considering the dispersion of the various launchers, then it is a figure worth noting in the historical record.

The descriptions of the V-weapon war fall into several incomplete historical narratives. One group of historians focuses on the technical aspects of these advanced weapons systems and the construction of the French launching sites. These works, while essential to understanding the vengeance weapon programs, generally fail to describe the effect of the bombing of these facilities on the French. British historian Norman Longmate typifies the second group of authors, who focus on the German use of these systems against targets in the United Kingdom. His books chronicle the suffering of the British living under these attacks and the determined efforts of fighter pilots to shoot down the flying bombs before they could do any damage. His is the narrative that most Englishmen who lived through that period can identify with. The third group of books is the official histories, which are the traditional sources for understanding the relationship of Allied bombing operations against these weapons, their launchers, and support facilities. In general, these historians see the commitment of bombers against these rocket sites as a diversion of precious air resources from their primary tasks, and they downplay their overall importance. All these traditional accounts fail to grapple with the damage bombing raids caused among the French towns and villages. Some historians have begun correcting this imbalance and are going beyond English-centric narratives and descriptions of construction and technical data. Regional historians, those who have grown up among the concrete ruins and have heard from their elders the stories of the bombing, have done the best work in this field. Finally, absent from almost all discussions are the forced laborers who constructed the massive concrete facilities. The thousands of people the Germans worked to death pouring concrete and digging into hillsides have been all but lost to history and assimilated into general discussions of the Holocaust. This group probably suffered from the Allied bombing in the same manner as other French civilians.

Vengeance Systems

Ultimately, three major systems emerged as Hitler’s vengeance weapons, his attempt to punish the English tormentors who refused to surrender to the logic of Nazi domination and continued to bomb German cities. Collectively, they represented a significant threat to the United Kingdom, the Allied war effort in general, and the invasion of northwest Europe in particular. Building the infrastructure for these systems was a massive effort that strained the German wartime economy. Constructing the dozen or so large launcher facilities, approximately ninety smaller launching sites, and a host of supply and storage installations drained workers and resources away from other construction priorities. Organisation Todt, the Nazi building contractor, had hoped to accomplish this work with volunteer and conscripted workers. There was never enough civilian labor, and ultimately it needed to resort to slave labor to keep the work on schedule. The first weapon placed into use was the Luftwaffe-designed flying bomb, the FZG-76 (Flakzielgerat 76), better known as the V-1 (Vergeltunswaffe 1) or Vengeance Weapon 1, intended to be launched from permanent sites. It was essentially a pilotless aircraft with a one-ton warhead and a unique-sounding pulse-jet engine. A magnetic-gyro compass guided it toward its destination. It flew at approximately 300 miles per hour until it ran out of fuel, a distance of 120 to 140 miles. Once it stopped, its one-ton high-explosive warhead crashed into the ground.

The second system was the Aggregat 4 or A-4, better known as the V-2 (Vergeltunswaffe 2) or Vengeance Weapon 2. Werner von Braun, who would later contribute to the American space program, developed it for the German army based on ideas developed by American scientist Robert Goddard. It was a long-range ballistic missile originally designed to be fired from fixed facilities in France and Belgium. In the last years of the war, this was the Nazi regime’s most expensive armament project and, in Hitler’s view, the best way to defeat the Anglo-American invaders. Each of these forty-five-foot systems traveled at more than three thousand miles per hour and carried a one-ton, high-explosive warhead. In open terrain, it could create a crater thirty-forty yards in diameter and ten to fifteen yards deep. Obviously, it was capable of doing widespread damage if it hit a city.

Crossbow Overview

As early as 1939, the British government was aware of several military rocket programs under development in Germany, and by the end of 1942 the intelligence services were receiving regular reports of rocket tests along the Baltic coast. Between January and June 1943, long-range reconnaissance flights had confirmed the existence of a testing area at Peenemünde, ninety miles east of Rostock, and had clearly identified the presence of rockets. At the same time, reports continued to accumulate about large-scale excavations and construction in the Pas-de-Calais and Manche departments of northern France. In April 1943 Churchill received his first detailed briefing on the possibility of long-range rockets aimed at London. The British Chiefs of Staff formed a special committee to monitor the developing threat and appointed a member of Parliament and Churchill’s son-in-law, Duncan Sandys, to head it. The primary task of this group was to figure out what the Germans were up to, what was the actual threat, and how the Allies could defeat it. A few members of the government doubted the existence of a rocket program, arguing it was a German hoax, but the evidence continued to accumulate as Sandys continued his investigation. Soon he had silenced their protests.

By early November 1943, the nature of the threat had become relatively clear as intelligence analysts realized that Organisation Todt was constructing three different types of installations in the Pas-de-Calais and the Cotentin Peninsula. Some of these were enormous, with deep excavations surrounded or covered by large amounts of concrete. These experts were still unable to determine their precise purpose but strongly suspected some innovative weapon. As a result, the Air Ministry, which had the best means of responding to enemy actions across the channel, took control of the investigation from Sandys’ committee and began to focus on the military aspects of the problem. Information continued to flow into London from a variety of sources, and by the beginning of 1944 it was evident that there were at least two different long-range weapon threats. Analysts reported that they had identified Flak Regiment 155W, with a headquarters in Amiens, which commanded 108 flying-bomb catapults designed to launch these unique aircraft. The prospect of rockets raining down on the United Kingdom could affect the nation’s will to fight and the Allies’ ability to invade the continent. Experts presented Churchill with estimates indicating that these rockets could inflict severe casualties upon the capital’s population, upwards of 30,000 killed and wounded. The British Chiefs of Staff were also concerned about the potential damage these weapons could do to the preparations for the landings in France. In the middle of December, they asked Frederick Morgan, still serving as the chief Overlord planner before Eisenhower’s arrival, about the potential effects of the rockets on the staging and execution of the invasion. They also inquired if he should consider mounting Operation Overlord from bases out of range of the vengeance weapons, such as harbors in Ireland, Northern Britain, or even the United States. The staff needed to know the chief planner’s thoughts and when they would have to make this decision. Morgan argued that the invasion had to be launched from the south, and he needed to know “at once” if he needed to make any significant changes in his plan. The chiefs directed no changes to the current preparations.

As the plan to deal with these weapons, known as Crossbow, emerged, it contained several distinct sets of action. Most immediately, the government developed a civil defense and security plan that integrated observers, detection devices, balloons, and interceptor aircraft. These improved on the measures developed earlier during the German air force’s bombing of London, but the staff was not overly optimistic about their effectiveness. The second aspect of the plan was the destruction of test sites and factories in Germany. The third and final portion of the operation was to destroy launching sites on the continent. They called this process Noball, which is the code name used for all missions and target lists against vengeance weapons in France.

The British public first became aware of this threat with the first V-1 attack, code-named Diver, a week after the Normandy invasion, during the night of June 12 and 13, when four bombs hit targets around London. A few days later, the barrage began in earnest with Flak Regiment 155W sending as many as one hundred flying bombs toward London each day. The most intense phase of this bombardment took place from June through the end of August 1944. During this period, the Germans controlled the French Pas-de-Calais region and used the plethora of modified launching sites scattered across the countryside. By June 18 the political panic within the British government was such that Eisenhower felt the need to pointedly tell Tedder that destroying Noball targets “are to take first priority over everything except the urgent requirements of the battle.” By July the British cabinet was debating using poison gas to contaminate launchers in France and as retaliation against the German homeland. Allied success on the battlefield muted such discussions, and as the Allies broke out of the Normandy bridgehead in July and began heading north, they overran these sites, sending the launch crews scurrying toward the Netherlands and Germany.

The first V-2 rocket attack, code-named Big Ben, hit London on September 8. There were few defensive measures the British could implement to stop the attacks. The rockets simply traveled too fast to be stopped by any system in the Allied inventory. The only effective defense was to continue to attack supply sites and factories in Germany. Rocket attacks continued against London and other cities in Europe until March 1945, when Allied ground forces overran most of Germany’s industrial area.

Executing Noball

British intelligence eventually identified four kinds of Noball targets in France: heavy sites, ski sites, modified sites, and supply and support facilities. It was the discovery of the nine large construction sites in the Pas-de-Calais region and the Cotentin Peninsula near Cherbourg that first captured the attention of British intelligence analysts. Throughout 1943 Organisation Todt’s building units, supported by thousands of slave workers and conscripted civilian labor, began excavating and building what British documents refer to as the “heavy” Crossbow sites. After the war, the Allies discovered that the German air force had responsibility for four of these, which were intended to store, assemble, and launch a large number of V-1 flying bombs. Code-named “Wasserwerk,” or water works, by the Germans to hide their purpose, these were primarily long tunnels with gaps in the ceiling to fire rockets toward London. In the Cotentin, they built one in Tamerville, northeast of Valognes, and the other at Couville, southwest of Cherbourg. The US Army’s VII Corps overran both of these installations in late June 1944. The other two were Lottinghen, east of Boulogne, and Siracourt, west of Arras in the Pas-de-Calais. Siracourt was typical of these kinds of launching sites. The dozen or so houses at the beginning of the war contained fewer than 140 citizens, mostly farmers and their families. The German army evacuated the French civilians as Organisation Todt arrived in the spring of 1943. On a little hill, just west of the village, contractors began construction in September. This facility was to be the first of four to process, store, and possibly fire the V-1. The main construction was 625 feet long and 132 feet wide and oriented at a right angle to London. The 1,200 workers, primarily Russians, Poles, Yugoslavs, and French forced labor, lived in a camp at Croix-en-Ternois a little more than a mile away. Under the supervision of Organisation Todt’s guard force (Schützkommando), the workers ultimately built the structure and poured more than 50,000 cubic meters of concrete to make it invulnerable to Allied bombers. Because of the bombing, however, it was impossible to finish its construction. As a result, the Germans never fired a flying bomb from it, and it fell to Canadian troops in September 1944.

The German army controlled the V-2 rockets, and it designed large concrete installations, capable of launching seven to ten rockets per day, with sophisticated storage and assembly capability. For example, the launchers at Wizernes, next to Saint-Omer, lay beneath a massive concrete cupola twenty feet thick and were capable of launching their rockets from two platforms. Other sites at Watten (Éperlecques), near Calais, and Sottevast, near Cherbourg, were just as massive and required millions of tons of concrete. Forty-four miles north of Siracourt and eleven miles northwest of the Luftwaffe airfields at Saint-Omer is the three-square-mile complex at Watten. On its southwest corner, Organisation Todt built a massive structure that came to be called the Blockhaus. It was an incredibly large structure that absorbed thousands of tons of concrete and the forced labor of thousands of unfortunate workers. Based on experience at the submarine pens along the coast, the German engineers expected it to withstand the bombardment of whatever the enemy could drop on top. The Allies never understood its exact purpose but knew they had to destroy anything that was consuming so much German effort. It was the first site detected by British reconnaissance. Duncan Sandys never believed it had an offensive capability and, even after his visit in October, considered it to be a plant for the production of hydrogen peroxide, which the Germans were using as a fuel. Postwar records and analysis indicate, though, that it may have served as a general storage, assembly, and launching facility in, according to one researcher, “a bomb-proof environment.” Most experts believe it was capable of launching rockets on its own.

Twelve miles south of the Blockhaus near Saint-Omer is the village of Wizernes. In an old quarry, Organisation Todt constructed one of the largest installations of the war, the V-2 launcher site known as La Coupole, or the dome, for the most impressive aspect of the facility. Todt designed it to assemble, fuel, and fire rockets from within the protected site. Upwards of 1,300 forced laborers worked on this project twenty-four hours a day. Like the Blockhaus, it had two launcher ramps that could fire rockets simultaneously and was probably the most sophisticated of the vengeance weapon launching sites. By March 1944 British intelligence was convinced that it needed to be added to the list of Noball targets. The most sinister of V-2 launcher sites was the silo complex west of Cherbourg near La Hague. These, generally overlooked by Allied intelligence, resemble the later American nuclear missile silos of the Cold War. It never became operational, and the US VII Corps occupied this region in July 1944. The problem for the Germans was that the construction crews could not hide the extensive work sites from the hundreds of Allied reconnaissance aircraft searching for signs of activity. The continuous bombing of the extensive excavations in France meant the Germans could not complete the launching facilities, which ended any possibility of the German air force using them. Ultimately, the Germans would fire no V-2 rockets from fixed sites but would employ mobile launchers that were essentially impossible for the Allies to detect in advance.

Eleven miles from Cap Gris-Nez, across the channel from Dover and ninety-five miles from the center of London, is a facility unique among the heavy sites. The British knew the Nazis were developing a long-range gun, but they did not know any details. The German army had done this before, and Allied commanders had visions of a weapon similar to the artillery used to bombard Paris in the previous conflict or the large guns deployed along the French coast. Therefore, most analysts believed the construction at Mimoyecques, France, was a variation on a V-2 launch site, since it bore no resemblance to anything with which they were familiar. Also, since most of the workers were German, few details emerged as to its actual intent. In reality, the site housed something revolutionary, a large battery of long-range guns, called Hochdruckpumpe (high-pressure pump) guns, later referred to by the Allies as Vengeance Weapon-3. Each 330-foot smooth-bore gun was to be capable of firing a six-foot-long dart about a hundred miles. Its range was the product of added velocity created by solid rocket boosters arrayed along the edge of the tube. Each projectile could carry about forty pounds of high explosives. The plan was to construct banks of five guns each with the potential of firing six hundred rounds per hour toward London. British intelligence knew little about what was going on inside the facility. After the war, Duncan Sandys’ investigation of the large sites discovered the true nature of the threat they had faced. Fortunately, Allied air attacks prevented Organisation Todt from ever finishing its work and German gunners were never able to fire these weapons.

The second kind of targets identified by Allied analysts were the so-called ski sites, named from the configuration of several buildings that looked like snow skis on their side. By late 1943 British intelligence officers had identified between seventy and eighty of these, hidden in the hundreds of wooden patches that dot the northwestern French countryside, with their launchers pointed directly at their intended target. If left alone, each one of these small installations could hurl fifteen FZG-76 flying bombs across the channel each day. The cumulative effect of hundreds of these striking London daily would not help civilian morale. They also posed a direct threat to the harbors from which the Allies would launch and sustain the invasion. One of the first sites identified by intelligence analysts was in the Bois Carré (Square Woods) about three-quarters of a mile east of Yvrench and ten miles northeast of Abbeville on the Somme. A French Resistance agent was able to infiltrate the construction site in October 1943 and smuggle out some of earliest detailed descriptions of a ski site layout. The long catapult, generally visible from the sky and quickly identified by reconnaissance aircraft, became the signature target indicator. As a result, even with extensive camouflage, they were identified, targeted, and destroyed by Anglo-American aircraft. As a result, none of these installations ever became operational.

Soon after the first air attacks, German leaders began considering an alternative method of launching the V-1. Security and concealment now became a priority, and these modified launcher sites were better camouflaged and of simpler construction. These new launchers no longer had many of the standard buildings, especially those that resembled skis, which had contributed to their rapid discovery by intelligence specialists. With minimal permanent construction, the only identifiable features were an easily hidden concrete foundation for the launch ramp and a small building to set the bomb’s compass. Other buildings were designed to blend into the environment or to look like the local farmhouses. All this took less than a week to fabricate, and forced labor no longer did the construction work, as German soldiers prepared each site in secret. Supply crews delivered the flying bombs directly to the launcher from a hidden location, assembled and ready to launch. All the teams needed to do was set the compass and mount it on the catapult. Difficult to locate from the air, these launchers would remain operational until overrun by Allied ground troops in early September 1944. After that, the Germans launched their V-1 rockets from sites in the Netherlands or from German bombers specially configured to fire these weapons.

One week after the last V-1 flew from French soil, the V-2 rocket made its first appearance when it slammed into a French village southeast of Paris, killing six civilians. The German army had abandoned any hope of using large fixed sites for anything other than storage, and they now organized the delivery of their rockets as mobile systems, structured around less than a dozen vehicles and trailers. While the rocket was still hidden, crews prepared it for launch, a process that took between four and six hours. Within two hours of mission time, the firing unit deployed to a previously surveyed site and erected the rocket on a mobile pad. As soon as it was on the way, the soldiers disappeared into the woods, leaving little trace of the launch. Unless an Allied fighter happened to catch the Germans during the short preparation process, there was little the air forces could do to prevent launches. The Germans fired none of the mobile V-2s from French soil, but fired them instead from Belgium, the Netherlands, and Germany. While not part of the discussion of bombing France, these rockets are an important reminder that the Germans continued to use mobile sites until the end of the war.

The final kinds of Noball targets were the supply sites that provided rockets for the individual firing units and the transportation network that supported them. By February 1944 the Allies had determined that seven facilities existed, one on the Cotentin Peninsula and the remainder arrayed just east of the belt of launchers. These, however, were relatively difficult to attack and were often located within underground bunkers or railroad tunnels, under fortresses, or deep within thick woods. They also were often protected by extensive anti-aircraft artillery. More vulnerable were the various rail yards that served as offload and staging points for these systems. Rail stations in Saint-Omer, Bethune, Lille, Lens, and Arras were the crucial nodes in this network. Attacking these transportation nodes also supported the goals of the Transportation Plan, the Allied attack of bridges along the Seine and Loire, and Operation Fortitude, the effort to deceive the Germans as to the actual location of the invasion.

 

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