British Defenses Against the Summer 1944 V-1 Bombardment

Cutaway view of the Fiesler Fi 103, or V-1 "Buzz Bomb"

Within a week of the Allied landings on Normandy on 6 June 1944, the Germans initiated a new form of bombardment against London, launching ten of Hitler's "Revenge Weapon No.1" or Vergeltungswaffe 1- V-1 for short. Of the V-1s launched in the early morning darkness of 13 June, six suffered failures that prevented them from even reaching the English coast from launch sites at Pas de Calais. Four bombs made it into British airspace, three of them hit in open land causing no casualties. One of those four V-1s, though, hit Bethnal Green, 2 miles from the famous Tower Bridge (which was used as the nominal aiming point) where it killed six people and injured nine more. British intelligence had predicted history's first cruise missile bombardment for a year, but the opening salvoes were far smaller than what was feared. It took three days to resume the launches and by 16 June 244 V-1s had been fired at the British capital. Of those missiles, 153 crossed into British airspace and of those V-1s, 73 hit the London area causing widespread damage and civilian casualties. 

German launcher crew prepare a V-1 on its firing ramp in France

In the three day lull following the first attack, the Royal Air Force and British Army swiftly deployed its defenses to southeast England. The first line of defense consisted of nine squadrons of Supermarine Spitfire and Hawker Tempest fighters as well as two squadrons of De Havilland Mosquito night fighters. The aircraft three lines of standing patrols, the first line 20 miles off the coast, the second line at the coast, and the third line 15 miles inland. Behind the fighter patrols came the gun zone made up of 192 heavy caliber AA guns and nearly 200 light-caliber guns in an area 20 miles deep. If a fighter pursued a V-1 into the gun zone, gunners were ordered to hold their fire to allow the fighter to complete its pursuit. Behind the gun zone on the southeast suburbs of London was the balloon zone made up of 480 barrage balloons. Over a quarter million mothers and children were evacuated out of London itself during the bombardment. Up to the end of June 1944, an average of 153 V-1s were fired at London. One-third failed or were shot down before crossing the English coast. Another one-third crashed or were shot down over southeastern England before reaching London. But that left a significant amount that managed to hit the London area. 

By mid-July, the defenses were revised based on the experience so far. This time each defensive measure was given a predefined zone for unrestricted engagement of any flying targets. The British Army's AA gun batteries were increased to 412 heavy guns and nearly 600 light guns in a 65-mile long strip along the coast that allowed the gun-laying radars of the batteries a clear view over the English Channel. Fighter pilots were prohibited from crossing the new gun zone, knowing that the gun batteries had unrestricted rules of engagement. The fighter zones were now split into two, with an outer zone over the English Channel that stopped five miles from the coast where the gun zone began. The inner zone began at the rear of the gun zone along the coast and extended back to the barrage balloon zone in London. In less than a month the number of barrage balloons increased to over 2,000. With the new defensive layout, over one-half of incoming V-1s were stopped from reaching the capital. 2 August would be the heaviest bombardment day, with 316 V-1s launched from 38 launchers in Pas de Calais. Of that number, 107 would impact in London. On that day, the nominal aiming point for the V-1 batteries in France, the Tower Bridge, took a direct hit from a V-1. 

A Spitfire pursues a V-1 at treetop height

By early August, the first Gloster Meteor jet fighter units were becoming operational and were tasked with V-1 interception. However, there were three developments that would vastly improve the British defenses, all technological wizardry courtesy of the United States. First was the SCR-584 gun laying radar that was the state of the art in 1940s radar technology and could lock onto targets instead of having to be manually directed by operators. A new device called the the Number 10 Predictor was the second device, it could exploit the improved fidelity from the SCR-584 to direct the AA fire more accurately. And the third bit of wizardry would also save many US Navy carriers and warships in the Pacific- proximity-fuzed AA shells that no longer needed a direct hit to bring down a target. With these three advances, the average V-1 engagement by a British Army gun battery only used a mere 156 rounds to bring down a V-1. 

The last V-1 launched from Pas de Calais came on 1 September, by which point the launch sites were all overrun by British Army units on the breakout from the Normandy beaches. From that point on, the V-1s that hit London were delivered by air-launching which was less effective and more prone to interception. During the first phase of the bombardment from June to September 1944, until the British defenses received new radars and proximity-fuzed AA shells, the most effective defense was actually the Allied air attacks on the French rail system. V-1 launch sites often had to wait days before receiving new missiles to fire due to attacks on supply trains and the rail network itself. Throughout this first V-1 bombardment phase, the launchers at Pas de Calais never launched V-1s at their intended capacity. 

The V-1's magnetic compass in the nose was enclosed in a wooden sphere

By far the most interesting defense that nearly got fielded in the summer of 1944 also came from the United States. Dr. Don Hare and his team at the Airborne Instruments Laboratory in New York were working on radio countermeasures systems when they were asked by the US government to assist in developing a counter to the V-1 attacks on London. Since the V-1 required no outside cues, it was invulnerable to jamming. Its direction guidance came via a magnetic compass in the nose that cued the master gyroscope that controlled the rudder. As the V-1 had to be simple to produce, it lacked any ailerons and its straight wing lacked any dihedral to provide stability. RAF pilots had already discovered a V-1 could be thrown off course and downed by forcing the bomb into a steep bank by tipping one wing. Dr. Hare's team reasoned that if a suitably strong magnetic field could be created, the magnetic compass could be tricked into cueing the master gyroscope to put the V-1 into a tight turn, thereby downing it. The American team's idea was to use existing railway lines that formed a loop around London 60 miles in circumference as a giant magnetic loop. By connecting specific rail lines in a giant circuit, it would take 1,000 amps of DC power to create a magnetic field over London that could confuse the V-1's autopilot. It was determined that 20 to 30 megawatts were needed which was within the capacity of a large commercial power station. Design work began on the needed equipment, but the "Mightiest Magnet" program ended when the launch sites in Pas de Calais were overrun by Allied forces. 

Source: International Air Power Review, Volume 27, Winter 2010/11. "Pioneers & Prototypes- Vergeltungswaffe 1- Adolf Hitler's revenge weapon" by Dr. Alfred Price and P.G. Cooksley, p150-159.

The Dismal Career of the Chinese Mosquito

During the Second World War, a second De Havilland Mosquito production line was set up at the De Havilland Canada facility at Downsview Airport in Toronto. A total of 1,133 Mosquito aircraft were built at the Canadian production line but when the war ended in 1945, there were 100 aircraft completed at Downsview that had not yet been accepted by the Royal Canadian Air Force. These aircraft were put into flyable storage and joining them were another 110 surplus Mosquito bombers that were part of a larger group that were excess to the end of the war effort and were divided up amongst several storage sites across Canada. The Globe and Mail newspaper ran a story on 20 May 1947 about the stored aircraft at Downsview that were worth approximately $30 million and would be sold to the highest bidder or scrapped.

In the late summer of that year, a delegation arrived in Toronto wanting to purchase the Mosquito aircraft. They were the Chinese Nationalist,s dispatched by Generalissimo Chiang Kai-Shek, that were in the midst of a civil war against the Communists led by Mao Tse-Tung. Interestingly Chiang had sent a group to Downsview in 1944 to evaluate the Mosquito but no sale resulted. Now fighting a bitter conflict for control of China, the Mosquito bombers represented an irresistible deal that would give Chiang the most modern and still in those days, fast bombers available. Though the details of the transaction have been lost to history, the estimate is that for $5 million the Chinese Nationalists got approximately 300 aircraft, though most were to be obtained to act as spare parts for the flying aircraft. Four hundred spare Merlin engines were also included in the deal which included disassembly of the aircraft for transfer to China and then reassembly there for the Chiang's forces. De Havilland Canada would also provide training for the first cadre of pilots at Downsview. 

By October, an assembly bay at the plant was turned over to a "disassembly" line as the aircraft were taken apart and crated for transport to China. Given the political sensitivities of the time, the sale was noted by the Canadian government as a "commercial sale" and all publicity of the transfer was discouraged. The first group of fifteen Chinese pilots to be trained at Downsview started their conversion in February 1948 with former RCAF Mosquito pilots as instructors. Having previously flown B-25 Mitchells, the Mosquito was quite a handful for the Chinese pilots and in short order seven had to be written off. To avoid any publicity, the training program was quickly shifted to China and that first group of pilots ended up writing off another nine aircraft, resulting in the Mosquito being nicknamed "Lin Tai Yu" by the Chinese, after an empress who was beautiful but wicked. 

Chinese flight training began with the second group in April 1948 and very quickly another 13 accidents occurred, this time with fatalities. Despite the presence of numerous De Havilland Canada technical specialists and ex-RCAF pilots in China, the accident rate continued. A second training unit set up by Chiang's forces resulted in the write off of five aircraft in only five days. Many of the accidents were in ground handling, so De Havillland's technical staff built a taxi trainer that had struts on the rear fuselage to prevent ground looping. The Chinese even managed to wreck that trainer! The Mosquito force that Chiang Kai-Shek wanted spent more time in training than in actual combat missions. Some of this was the quality of his pilots, but a lot of it was that the Mosquito was simply too much airplane for what was a Communist guerrilla insurgency. With the Communists advancing and gaining control of more of China, the Canadians noted the deteriorating situation as the local currency was falling and non-Chinese citizens were leaving the country in droves. 

On 10 December 1948 the capital, Peking (now Beijing) fell to Mao's forces and the De Havilland team was ordered to depart immediately. Most of the team managed to escape via Hong Kong, but some of the lead engineers found themselves "retained" by the Nationalists to help keep their aircraft flying. De Havilland Canada's management arranged for a special DC-6 flight to get this last group out of China. Nationalist soldiers refused to allow the Canadians to depart, but gunfire on the airfield perimeter from advancing Communist forces provided a distraction for the Canadians who managed to successfully depart as the airfield came under attack. 

Needless to say, much like the less-than-salutory operational career of the Martin B-57 by the South Vietnamese Air Force in 1965, the career of the otherwise brilliant De Havilland Mosquito in China was very much a failure and an unusual footnote to the history of the Mosquito. 

Source: De Havilland in Canada by Fred W. Hotson. CANAV Books, 1999, p120-121. 

Although the USAAF used the De Havilland Mosquito PR.Mk XVI primarily in the photo-reconnaissance role in Europe, there were two lesser-known types of missions flown by the two squadrons of the 25th Bomb Group at were equipped with the Mosquito.

"Mickey ships" were specially-modified Mosquitos that were equipped with the H2X radar set used on the B-17 Flying Fortress. A bulged nose housing held the H2X scanner with the amplifier and electronics crammed in the nose and bomb bay. The radar scope itself, though, was in the rear fuselage. Before the approach to the target, the observer had to climb over the equipment in the bomb bay and into the rear fuselage where he either photographed the radar display or filmed it with a movie camera. The purpose of the "Mickey ships" was to get radar navigation images of the approaches to German targets. These images would be then correlated with maps to provide the B-17 navigators with poor-weather approaches to high-priority targets in Germany.

The H2X drew a current that often was more than the electrical system of the Mosquito and the equipment often arced, aborting the mission. If bailout was necessary, the observer had to climb over the equipment and jump out the bomb bay- assuming of course, the crew remembered to open the bay doors.

The other lesser-known USAAF Mosquito mission was code-named "Red Stocking" and were done in conjunction with the OSS, the CIA's predecessor. Equipped the special equipment, the Red Stocking Mosquito flights flew deep into Germany to detect and record UHF transmissions from OSS agents in the field. The bomb bay was modified to take the receiving equipment, an oxygen system, and accommodations for the observer who operated the receiving set.

The OSS agent carried what was called the "Joan-Eleanor" device, which was a four-pound radio set that beamed the agent's reports on a very narrow beam that was nearly impossible for German counterintelligence to detect via triangulation. A Red Stocking Mosquito would fly overhead a predetermined point at a particular time so the OSS agent could point the Joan-Eleanor antenna in the right direction. The missions were flown singly and at high altitude, often at night. In one mission, a Red Stocking flight circled over Berlin at over 30,000 feet to communicate with several OSS agents in the city.

Source: Wings of Fame, Volume 18. AIRtime Publishing, 2000, "de Havilland DH.98 Mosquito (Bomber and PR Variants" by Martin Bowman, p84-87.

In 1943 a DeHavilland Mosquito in BOAC markings landed at RAF Leuchars in Scotland carrying a valuable passenger- Danish physicist Niels Bohr, the 1922 winner of the Nobel Prize in physics. In a conference in Washington DC in 1939, Bohr detailed how the uranium isotope U-235 could be used to create a chain reaction in an atomic bomb. By 1943 the Nazis were rounding up and deporting the Jews in Denmark and as his mother was Jewish, Bohr was at risk. Word got out that he was about to be arrested and given the choice between joining Hitler's atomic weapons project or be sent with his family to a concentration camp.

With the help of the British secret service, Bohr was smuggled to Sweden and then flown in an improvised bunk in the bomb bay of the Mosquito from Stockholm to Scotland. From there he was flown onward to England and then the United States to join the Manhattan Project.

The Mosquito flew approximately 200 flights in BOAC colors between Stockholm and the UK during the war conveying clandestine personnel and war materiel. Only the Mosquito was fast enough to evade patrolling German fighters over the North Sea.

Source: Aviation History, September 2009. "The Magnificent Merlin" by Nicholas O'Dell, p32.