ROUND ONE: THE AIR OFFENSIVE

The RAF’s nighttime raid against Peenemünde on August 17–18, 1943, and the USAAF’s daylight raid against Watten ten days later marked the start of an aerial offensive against the V-weapons that did not cease until May 1945. Operation CV, as the effort came to be called, was the strangest bombing offensive conducted during World War II. With their southern cities threatened, the British diverted Allied heavy bombers from strategic bombardment in Operation POINTBLANK, the destruction of German industry, and from interdiction bombing in Operation OVERLORD, support for the invasion of France. The use of heavy bombers contradicted U.S. studies demonstrating that fighter-bombers operating at low altitude were more strategically effective and cost effective in destroying V-site targets. The British and the Americans argued over what priority CROSSBOW missions should have relative to other offensive aerial missions, and in the end the Allies undertook an ill-conceived campaign against an ill defined threat. Allied air commanders remained uncertain what results, if any, they were producing—a terrible burden in light of the real cost in lives and aircraft. At times, Operation CROSSBOW appeared to be much more a political than a military solution to the problem of the V-weapons, a demonstration that any German terror bombardment of London would be met by a counteroffensive of some kind. D-Day came and passed with no Nazi vengeance strikes, so the Allies relaxed. When the Germans finally did launch V–1s in June through August of 1944, the Allied response was immediate and drastic—but probably ineffective.

The RAF Bomber Command raid against Peenemünde on August 17–18, 1943, used the most sophisticated bombing techniques available at the tactical and operational levels. Five hundred ninety-six bombers of mixed type—including Short Stirlings, Avro Lancasters, Handley-Page Halifaxes, and de Havilland Mosquitoes—used pathfinders, aiming points, time-and-distance bombing, and a master bomber for coordination. The raid was executed in waves, accompanied by a feint against Berlin to draw off fighter opposition. Nonetheless, the RAF lost forty bombers and 290 men, most of those in the latter waves after German interceptor defense forces realized what was the true target.

The August 27, 1943, USAAF daylight raid against Watten, on the other hand, was more typical of the sledgehammer approach. The Eighth Air Force dispatched 187 B–17F (Flying Fortress) heavy bombers, flying at high altitude. Their mission was to destroy that large, fixed target. For good measure, smaller raids of Eighth Air Force medium and heavy bombers attacked Watten again on August 30 and September 7.

Both Peenemünde and Watten were Allied tactical successes but strategic failures. The Peenemünde raid did heavy damage to installations and killed some key personnel, but it alerted the Germans to the fact that the Allies considered the V-weapon program a serious threat. German commanders promptly relocated production facilities elsewhere. The Watten raids proved premature. British intelligence estimated that the American raids would delay construction of the Watten large site about three months, but that delay was ultimately overshadowed by scheduling problems in the V–2 program itself. Meanwhile, using Mosquito fighter bombers, the RAF’s Second Tactical Air Force bombed the large site at Mimoyecques twice in early November and in late November and early December struck the large site at Martinvast with 450 tons of explosives.

Duncan Sandys’ BODYLINE committee transferred its responsibility for investigating the extent of the V-weapons systems to Britain’s Air Ministry. The task of finding, photographing, and assessing targets had grown so large that it had to be handled by regular intelligence departments and operational staffs instead of a committee. On November 15, 1943, the codename BODYLINE was replaced by the new name, CROSSBOW. The Joint Intelligence Subcommittee of the British Chiefs of Staff wrote its first CROSSBOW report nine days later and presented its findings before the British War Cabinet on November 29. The War Cabinet ordered another massive reconnaissance and steadfast bombing of the chain of ski sites in northern France.

The CROSSBOW aerial reconnaissance mandated by the War Cabinet began on December 4 and covered a swath of territory 150 miles wide southeast of London and Portsmouth. PRU Spitfires and other aircraft identified sixty-four ski sites—two dozen more than had been seen a week earlier. By the third week of December, the identified total had risen to seventy-five. Allied generals decided to begin bombing the sites as soon as possible, using tactical air forces then being marshaled for Operation OVERLORD. U.S. Lt. Gen. Ira Eaker, commanding the USAAF in Britain, agreed with a suggestion by Air Chief Marshal Sir Trafford Leigh-Mallory, Allied Expeditionary Air Force (AEAF) commander, to attack any of the ski sites that seemed to be more than 50 percent finished. Eaker told Lt. Gen. Lewis Brereton, commanding the U.S. Ninth Air Force, to prepare for strikes using Martin B–26 Marauder and Douglas A–20 medium bombers, joined by Mosquitoes, Marauders, and Havocs of the RAF Second Tactical Air Force. On December 3, the British War Cabinet approved this AEAF and Air Ministry plan, and a few hours later Eaker directed Brereton to begin Ninth Air Force CROSSBOW operations with the highest priority. Although hampered by poor weather, the operations began two days later.

The air leaders’ problem was not only to determine what to strike and how to strike it, but also how often to strike—a problem the Allies never really solved because it was impossible to know whether specific raids were effective. One well-placed 2,000-pound delayed-action bomb could do more damage than twenty five 500-pound bombs scattered indiscriminately from a high altitude. On the other hand, the more bombs dropped on a given area, the higher the probability that at least one would find its mark. Analysts in the Air Ministry’s CROSSBOW agency and personnel in several Allied air forces tried to estimate the number of attacks and the tonnage of bombs needed to do serious damage to a ski site.

With Allied combat air patrols having swept the skies almost clean of German fighter interference, heavy bombers on short-run, high-altitude missions could drop more bombs with relative impunity. Less fuel was needed for the short sortie from England to France, so more bombs could be carried. For example, a Mosquito had a maximum bomb load of one 4,000-pound “blockbuster” bomb. To deliver its explosive with any accuracy the Mosquito had to make a mid-to-low-level attack run through vicious ground-based antiaircraft fire. But with just enough fuel for a 300-mile roundtrip, a Lancaster could carry a bomb load of almost 18,000 pounds. That bomber did not have to be so precise, could remain at high altitudes, and consequently could fulfill the mission at less risk to aircraft and crew.

At least that was the theory: high efficiency, low risk. But was the risk of using heavy bombers any lower than using other bombers? Losses happened about 1 percent of the time; during the nearly 37,000 sorties ultimately flown by the RAF Bomber Command and the USAAF Eighth Air Force against CROSSBOW targets, about 400 heavy bombers were lost. Under poor operating conditions, the USAAF Ninth Air Force and RAF Second Tactical Air Force lost about 1 percent of medium bombers. Later studies showed that Mosquito missions actually were safer than any other type of aircraft used in CROSSBOW.

On the basis of early results, the British concluded that medium bombers operating at lower altitudes were ineffective against V-sites. On December 15, 1943, the British Chiefs of Staff decided to ask the Americans to use the Eighth Air Force’s heavy bombers in the CROSSBOW offensive. At that point, Eaker did not see those missions as diversions from Operation POINTBLANK’s bombing of Germany; the vagaries of winter weather sometimes made it impossible to strike primary targets in Germany but possible to attack targets in France. As it happened, however, bad weather hampered activities on both fronts and it was not until Christmas Eve that the Eighth Air Force made its first CROSSBOW attack.

More than 1,300 aircraft participated in mission number 164, the largest Eighth Air Force operation to that point—even larger than the raid on Schweinfurt-Regensburg. Six hundred seventy B–17s and Consolidated B–24 Liberators, escorted by Republic P–47 Thunderbolts, North American P–51 Mustangs, and Lockheed P–38 Lightnings, dropped 1,700 tons of explosives on twenty-three ski sites. The size of the mission demanded some explanation, and through various sources war reporters learned more than even the U.S. aircrews knew—namely, that the Allies were pounding installations connected with the long-anticipated German vengeance weapons.

USAAF aircrews might not have questioned the bombing, but U.S. military leaders harbored grave doubts about it. They wanted to cooperate with the British, who were supplying intelligence for CROSSBOW, but they had questions about the extent of the German V-weapon program, how far it had progressed, and the threat it actually posed. The Watten raids had been directed against a large site, not the compact ski sites, and it had never been clear that Watten was a V-site. On December 22, U.S. Army Chief of Staff Gen. George Marshall asked Lt. Gen. Jacob L. Devers to get answers to the questions. Devers arranged for a courier to fly from England that night to bring sketches of a ski site to the United States.

Marshall realized that the British were not sharing information immediately, partly because of their own internal disagreements over what the photographic evidence revealed, and he recommended to U.S. Secretary of War Henry L. Stimson that he appoint a U.S. committee to assay the V weapon threat independently and to suggest a course of action. On December 29, Stimson assigned the director of the War Department’s New Developments Division, Gen. Stephen G. Henry, to chair that committee. Henry was to make sure that everyone—the War Department, the U.S. Navy, and especially the British—coordinated closely on fact-finding and problem-solving. If the V-weapon threat was so acute (and that must be the case if the Air Ministry and British Chiefs of Staff were requesting massive help from the Eighth Air Force), why hadn’t British intelligence told their U.S. counterparts about it sooner? And why were heavy bombers supposedly more effective in attacking V-sites than were medium bombers? Did the British have other information that they were not sharing? Marshall sent a curt memorandum to the highest-ranking British officer in the United States, declaring that the USAAF could offer no help until U.S. leaders understood why CROSSBOW should claim aerial resources from either Operation POINTBLANK or Operation OVERLORD.

The British Chiefs of Staff had already discussed this issue with Lt. Gen. Sir Frederick E. Morgan, chief of staff to Supreme Allied Commander Gen. Dwight D. Eisenhower. Morgan was responsible for presenting information and options to Eisenhower and he served as a useful liaison between the British and the Americans. The British Chiefs of Staff had asked if the Vweapon threat had advanced sufficiently to jeopardize the Operation OVERLORD invasion of France planned for the spring of 1944. Yes, Morgan replied, but not enough to prompt a change of plans or a postponement of the invasion. The V-weapons had to be considered a reintroduction of German air power, limited and cumbersome to wield and likely to cause the Allies grief, but unlikely to ruin the invasion. He said that the threat of V weapon bombardments of London and Portsmouth would prove a greater political problem than a military one. British military leaders did not want to exaggerate the V-weapon strategy’s ultimate effect on the outcome of the war, but neither did they want to lose U.S. support for an aerial counteroffensive that might prevent or reduce bombardment of the British Isles. The U.S. leaders might decide to continue with Operation POINTBLANK and leave Operation CROSSBOW to RAF Bomber Command, and what if Bomber Command alone could not stop the V-threat?

It suited British purposes that General Henry’s U.S. CROSSBOW committee initially assumed the worst. Committee members went through precisely the same reasoning process as had the BODYLINE investigation committee six months earlier: massed V–1 attacks could overwhelm antiaircraft defenses, and if the rumors of the supersonic V–2 were correct, there was no defense against it. The Germans were capable of using biological or chemical weapons against military and civilian targets. Until more information on the V-weapons’ production, transportation, and assembly methods could be obtained, the only targets to attack were the launch sites, assumed to be the large sites and the ski sites, but ground or airborne assault was impractical.

By early 1944, the U.S. CROSSBOW committee concluded that the best defense would be a good offense—hit the V-sites before the vengeance weapons hit London, but committee members doubted that diverting heavy bombers from POINTBLANK strategic bombing missions was the best strategy. In January and February 1944, thirteen of twenty-nine missions flown by Eighth Air Force bombers had been directed at CROSSBOW targets, but plenty of U.S. fighters and medium bombers were staged in England awaiting Operation OVERLORD. Could these be used more effectively against ski sites and underground bunkers than the Eighth Air Force’s high-altitude Flying Fortresses?

Henry’s committee asked the USAAF to determine the best method of attacking CROSSBOW targets. Because the strategic Eighth and tactical Ninth Air Forces based in England would be providing actual firepower, it seemed reasonable and pragmatic to fly the missions and then study the results. Army Chief of Staff Marshall approved that suggestion on January 12, 1944. The commander of the Army Air Forces, Henry H. “Hap” Arnold, wanted to study further the best method for destroying V-sites, particularly the ski sites, and he argued successfully that every type of aircraft the USAAF had in operation—fighters, medium bombers, and heavy bombers—should be flown with different bomb payloads in test attacks against mock-up sites. The attacks would take place under war game conditions against real antiaircraft units.

The responsibility for marshaling the aircraft, bombs, antiaircraft guns, and, most importantly, construction workers and materials to create simulated V-1 sites from scratch fell to the USAAF Proving Ground Command at Eglin Field in the Florida panhandle, commanded by Brig. Gen. Grandison Gardner. On January 25, Arnold telephoned Gardner and told him to do the impossible: reproduce simulated V-sites within days. “It will take a hell of a lot of concrete,” Arnold said bluntly. It did, and a few civilian toes were stepped on in the process. Gardner sent purchasing agents hundreds of miles in every direction to buy all the available brick, lumber, concrete, cement, and steel from any supply source they could find.

During February and March, the Americans began building V–1 sites in Florida much faster than the Germans were building them in France. Army Ground Forces sent camouflage units and a full antiaircraft battalion by truck and train. Most of the construction materials for the Eglin Field mock-ups arrived by aircraft, trains, and trucks, and thus showed that the French-Belgian-German rail and road transportation system would be a legitimate CROSSBOW target.

In February 1944, Eglin Field boasted the largest construction/destruction project on the Eastern seaboard. No sooner would a target building and site stand complete than airplanes would flatten it. Experts rated the destructive force of different kinds of bombs, how effectively different aircraft delivered them, and the success rate and risk of different attack techniques. Studying the reports, Gardner learned that lightning-quick, low-altitude attacks maximized damage and minimized aircraft risk. The key points were to (1) give antiaircraft defenses as little warning as possible, (2) hit the site with a delayed-action 1,000- or 2,000-pound bomb from a very low altitude, and (3) get out fast. The damage was substantial, but not necessarily a knockout blow; repeated raids would deliver that. The quick raid well suited fighters such as the P–38 or fast bombers such as the Mosquito. On February 19, Gardner invited Arnold and British Air Marshals Norman H. Bottomley and Frank Inglis to watch a demonstration at Eglin Field. The British were impressed; Arnold was convinced.

On March 1, Gardner prepared a final report outlining the tests’ conclusive findings that treetop-level attacks by fighter-bombers were just as effective against ski sites as were attacks by medium- or high-altitude bombers, and at less cost and with less risk. It was not necessary to divert Eighth or Ninth Air Force heavy bombers from POINTBLANK strategic missions. Gardner went to England in mid-March with a special mission of U.S. officers to discuss the Eglin Field tests with Eisenhower at Supreme Headquarters Allied Expeditionary Force (SHAEF) and with British and U.S. air commanders at air headquarters and air bases.

USAAF Generals Arnold, Brereton, and Hoyt S. Vandenberg, and U.S. Strategic Air Force in Europe (USSTAF) Commander Gen. Carl Spaatz were eager to introduce the minimum-altitude bombing technique. To their surprise, British Air Chief Marshal Leigh-Mallory insisted on continuing to use heavy bombers at high altitude. He believed the Eglin Field tests had been conducted under ideal rather than real-world conditions, and that enhanced antiaircraft defenses around the V-sites posed even greater risks to low-flying aircraft. Leigh-Mallory had other information that he did not immediately share with the U.S. commanders: British intelligence had learned in early February that the Germans had seen the vulnerability of the ski sites and were constructing less elaborate, modified sites that were more easily camouflaged. Leigh-Mallory believed that the smaller, harder-to-find targets would be more easily and safely hit by high-altitude scattered-area bombing.

Arnold was angered at what he perceived to be British obstinacy and an apparent penchant for theoretical analysis over hard evidence. He considered the Eglin Field studies more real-world than Britain’s guesswork. Neither he nor Spaatz wanted Operation CROSSBOW missions to interfere with the strategic bombing of Operation POINTBLANK. How, he wondered, could the British justify diverting heavy bombers from POINTBLANK without solid evidence to contradict the findings of the Eglin Field tests? Arnold was even angrier on February 13 when, at British insistence, the Combined Chiefs of Staff gave CROSSBOW priority over all Allied bombing missions except the destruction of the German interceptor airframe industry. That would remain Allied policy unless and until Eisenhower changed it. As a result, the Allies dropped 4,250 tons of bombs in 2,800 CROSSBOW sorties during March, most of them against ski sites.

British anxiety over the V-weapon threat mounted in April 1944. Photographic reconnaissance of the large, ski, and modified sites showed German and forced-labor construction battalions continuing to rebuild shattered venues and to complete new ones. Intelligence received reports of many V–1s being dispersed throughout northern France. All of this implied that the V–1 offensive might begin in mid- to late April. Although Allied bombers had inflicted “Category A” damage (an estimate that it would take the Germans two months to rebuild) on many ski sites, it appeared that CROSSBOW was failing.

On April 18, the secretary of the British War Cabinet, Sir Hastings Ismay, urged Eisenhower to step up attacks against all suspected V-sites. The British conceded that the campaign to that point had been a failure, but now they demanded more resources for the struggle. Eisenhower deliberated and the next day granted CROSSBOW missions priority over all Allied air operations. By the end of the month, the CROSSBOW campaign had increased in volume by about 50 percent; Allied aircraft, mostly heavy bombers, dropped a total of 7,500 tons of bombs in 4,150 sorties. Although they believed that Operation POINTBLANK was the key to defeating Germany, Arnold, Spaatz, and other U.S. air commanders had to defer temporarily to CROSSBOW. Spaatz concluded that if things kept up this way, he would not have enough aircraft to support Operation OVERLORD, much less Operation POINTBLANK.

Arnold was unwilling to concede the POINTBLANK strategic bombing campaign in favor of CROSSBOW. In early May, he sought fresh evidence that the Allies should switch from high-altitude, heavy bomber strikes to minimum-altitude, fighter-bomber strikes. If results from the Eglin Field Proving Grounds did not convince the British, perhaps results from theater operations would. Spaatz reported that four P–47s, each armed with two 1,000-pound delayed-action bombs, used the Eglin Field minimum altitude technique to attack four ski sites. Three of the four fighter pilots scored Category A damage despite heavy antiaircraft fire. Eighth Air Force commander Maj. Gen. James Doolittle reviewed statistics from Eighth Air Force missions and showed that Mosquito fighter-bombers had achieved the best results with the fewest losses.

As D-Day neared without any sign of a V–1 offensive and U.S. military strategists increased their pressure, the British lessened their insistence that CROSSBOW take higher priority than POINTBLANK and OVERLORD. The Allies had pummeled ski sites with Category A damage 107 times, and most of the sites were ruined. By early May, ski sites were no longer listed as primary targets. Heavy bombers, mostly Eighth Air Force B–17s, and medium bombers each accounted for about one-third of these strikes; fighters and Mosquitoes had accomplished the remaining one third. Those statistics, more than any others, supported the U.S. contention that the use of heavy and medium bombers was wasteful. And it did not help the British position that RAF Bomber Command had flown nearly one-sixth of all CROSSBOW sorties without once scoring Category A damage. Between December 1943 and June 1944, the Allies flew more than 25,000 sorties and dropped over 36,000 tons of bombs on CROSSBOW missions. In that effort, the Eighth Air Force lost 462 men and forty-nine heavy bombers; the Ninth Air Force lost 148 men and thirty medium bombers; and other USAAF and RAF units lost 161 men and seventy-five aircraft of mixed type.