June 6th 2019 marks the 75th anniversary of D-Day when, during World War 2, the Allies launched the invasion of Normandy. In this special commemorative feature we take a look at some of the many ways Allied air operations contributed to the success of this daring assault on Nazi-occupied north west Europe.
As early as 1942 RAF photoreconnaissance (PR) Spitfires were flying missions to photograph potential landing beaches along the French coast, taking vertical images at different states of the tide so that planners could calculate their gradients. This was vital information, as the gradient of a beach would determine how close inshore a landing craft could get before grounding.
Other reconnaissance tasks undertaken by RAF aircraft in preparation for D-Day included taking photographs for mapping purposes as there was a shortage of survey-standard imagery available to produce the detailed 1:25,000 and 1:12,500 sheets that would be needed for a successful invasion.
Allied reconnaissance aircraft also gathered intelligence on German coastal defences. USAAF Lockheed F-5E Lightningsundertook‘dicing’ missions, flying along beaches at a speed of 375 mph and height of just 25 feet to get close-up images of the deadly anti-invasion devices deployed by the Germans.
The success of the D-Day landings depended on the Allies having control of the skies above the invasion beaches. The Pointblank Directive of June 1943 ordered RAF and USAAF bombers to target German factories involved in aircraft production with the aim of significantly reducing German fighter strength in advance of the planned invasion.
The majority of the ‘Pointblank’ attacks were daylight ‘precision-bombing’ raids by USAAF B-17 Flying Fortresses and B-24 Liberators. American bomber losses were initially very high but the tide turned with the arrival of the very capable P-51 Mustang escort fighter which had sufficient range to provide protection for the bombers all the way to their targets.
During ‘Big Week’ (20-25 February 1944) the Americans launched a series of raids that they knew would provoke a significant response from the German fight force.
In the ensuing air battles, often occurring far from the bomber streams, the Mustangs proved very effective against German twin-engined fighters, and also the bomber destroyer version of the Fw190 that lacked manoeuvrability because it was fitted with heavy underwing canons. The Germans lost many fighters and, more significantly, many pilots too. These losses were unsustainable.
Operation Pointblank ended in April 1944 by which time the Allies had effectively gained air superiority over Europe.
From mid March 1944 up until the eve of the invasion, RAF fighter-bomber Spitfires and Typhoons systematically attacked radar installations in Normandy (and indeed elsewhere along the French and Belgium coasts so as not to give the game away). This added to the Luftwaffe’s difficulties, although some of these heavily defended stations still remained operational at the time of the invasion.
Allied air forces flew over 14,000 sorties on D-Day: transporting troops, attacking German defensive positions and communications routes on the ground, and patrolling the skies above the landing beaches. For the most part, these allied sorties went unchallenged by the depleted Luftwaffe.
Although the threat of attack from the Luftwaffe had been reduced, there was still a possibility that the plethora of allied aircraft types in the crowded skies above Normandy could be misidentified and accidentally shot down by ‘friendly fire’. To minimise the chances of this happening, the wings and fuselages of all allied aircraft were painted with distinctive black and white stripes to aid identification from the air and from the ground.
A series of elaborate deception exercises also helped the Allies gain a foothold at Normandy by tricking the Germans into believing that the invasion would take place elsewhere.
In the early hours of 6 June, in two covert operations code-named ‘Taxable’ and ‘Glimmer’, RAF Lancaster and Stirling bombers flying in very precisely defined patterns dropped strips of metal foil (known as ‘Window’) that caused German radar operators to believe that invasion convoys were headed to other locations (Le Havre and Boulogne) along the French coast.
RAF Air Sea Rescue launches carrying electronic signal repeaters and towing barrage balloons containing radar defectors helped to reinforce this illusion.
In another deception exercise - “Operation Titanic’ - RAF aircraft undertook fake airborne assaults by dropping 500 dummy parachutists in four locations away from the actual invasion drop zones.
Around 1200 allied transport aircraft took part in the initial aerial assault on D-Day involving three airborne divisions.
Many parachutists were carried into action aboard the Douglas C-47 Skytrain (known as the DC-3 Dakota in British service), a rugged and dependable workhorsethatwas basically the military version of a successful pre-war airliner. The Dakota could accommodate 27 fully equipped troops. Of the many aircraft types used by the allies on D-Day, it is arguably the Dakota that is most closely associated with the operation.
Other airborne troops were transported in gliders that were towed into the battle zone by tugs. The time taken for gliders to land following release from the tug was kept as short as possible to reduce their exposure to ground fire.
The backbone of the British glider fleet was the Airspeed Horsa, a wooden aircraft capable of carrying 25 troops and a crew of two. A six-pounder anti-tank gun and jeep could be carried instead.
The American equivalent was the Waco CG-4A. The fuselage was made of tubular steel covered in fabric, the wings of wood. This aircraft could carry 15 troops with a crew crew of two or a 75mm howitzer and a crew of three.
The British also developed the Hamilcar glider - the largest glider of the war, capable of carrying a seven-ton tank. 70 of these gliding behemoths took part in the D-Day landings, towed by Handley Page Halifax tugs, the only aircraft powerful enough for the job.
Once the Allies had gained an initial foothold in Normandy, they set about consolidating their position in preparation for the land battles ahead. There was a need to provide airfields quickly to support the advance, but runways and aircraft maintenance facilities were in short supply in Normandy due to allied air attacks ahead of the invasion aimed at securing air superiority.
So dozens of temporary airstrips were constructed to provide the necessary operational capacity. These fell into four categories, each category based on the level of facilities available - Emergency Landing strips (ELS), Refuelling and Rearming Strips (RRS), Advanced Landing Grounds (ALGs) and Airfields proper.
Potential sites for airstrips were selected ahead of the invasion and specialist teams of surveyors, engineers and construction workers supported the construction effort. The British utilised one RAF Construction Wing and five Royal Engineer Airfield Construction Groups, and the Americans seventeen USAAF Engineer Aviation Batallions.
Rather than simply rely on dirt or grass landing strips, specialised pre-fabricated materials were used to create landing and take-off surfaces where operational need or local conditions dictated this. Four such materials were utilised: Sommerfield Track, Square Mesh Track, Prefabricated Bitumised Surfacing (PBS) (aka Prefabricated Hessian Surfacing) and Pierced Steel Plank (PSP). Author Jonathan Faulconer gives a detailed and fascinating account of how these materials were deployed in the Haynes D-Day Operations Manual.
For more information, check out the relevant Haynes publications via the links in this article.