D-Day...in Brief

Précis of Events

Most people, on learning that a small group of RAF ground-based personnel landed from a D-Day invasion fleet on a hostile beach, would have a question: Why was such a group included in an operation usually undertaken by specialist, frontline infantry?

The answer is that the frontline infantry needed the best possible aerial protection, both on the beaches and as they moved forward to secure the beachhead. Therefore, it was absolutely necessary that the Allied Air Forces provided radar detection and guidance to be in place on the evening of the D-Day invasion.

So it was that a relatively small force of about 160 Royal Air Force technical personnel, together with their attached, supporting Signals and other units, were scheduled to land on Omaha beach in Normandy at high tide (about 11:00hrs), immediately after the first waves of American assault troops had secured the beach and their Engineers had made it safe.

Why, then, was it not American radar specialists that landed with their assaulting troops rather than Royal Air Force personnel?

The simple explanation is that the Americans did not have their own radar available by D-Day.

It was therefore agreed by the Government of the United Kingdom that one of its own Mobile Ground Controlled Interception Radar Units, (GCI 15082), would be lent to the Americans.

The loan of the British radar was intended to last only until 21st July 1944, 6½ weeks after the D-Day landings but, in the event, the loan lasted a further two months – until 22nd September 1944. The British mobile radars, being able to detect the range, bearing and height of potential enemy aircraft, were ideally suited for this role, provided they could be located on favourable sites and were available for immediate use on the night of the landings.

Planning for an invasion of Europe began as early as April 1942. It was not until May 1943, though, that we learnt that an Anglo-American conference in Washington considered the opening of a front in Western Europe for offensive operations against Germany. It was then that Allied planners selected 50 miles of coast in western Normandy, from the Vire Estuary to the Orne, as the assault area for securing a lodgement. Initially, it is believed that only three beaches were chosen as the invasion sites (Juno, Gold and Utah) but as plans developed, it was ultimately decided that two further beaches would be needed. Thus, Sword beach was added to the east and Omaha to the west.

It was most strongly recommended that these radar units should be given, as soon as possible, the necessary experience in living, working and operating in the open air, under conditions parallel to those they were likely to meet with on the Continent. It was also stressed in this connection that there would be a need for ensuring at all times, in the interest of operational efficiency, the provision of a reasonable standard of comfort in the field. To this end, the men selected to form the Mobile Radar Units and their supporting Signals Units began training and operating their equipment in mid-1943. This training included what were called “wet-shod” landings in Scotland, (i.e. practice landings from landing craft), and also a degree of training more usually associated with front-line infantry.

GCI 15082 was formed as a Ground Controlled Interception unit in August 1943 at Renscombe Down, near Swanage in Dorset. It was equipped with what was then the latest in radar, including height-finding apparatus, and it was used primarily for the control of night fighters in forward fighting areas. The unit was mobile, with heavy equipment mounted on Crossley trucks and smaller apparatus on Bedfords. Operational status, following arrival at a designated site, was expected to be reached in two hours.

In order to provide this air cover, three Base Defence Wings, (in May 1944, re-designated Sectors – BDS), were begun to be formed from 1st January 1944 with the appointment of Group Captain Moseby as the Commanding Officer of No. 21 BDS at RAF Church Fenton, North Yorkshire. At a later date, the second and third Wings, Nos 24 and 25, were formed, the former with effect from 1st February 1944 at RAF Acklington, Northumberland, and the latter with effect from 1st March 1944 at RAF Castle Camps, Cambridgeshire.

Prior to this, the technical elements of the mobile ground-controlled interception radar units (GCIs), which had begun to form in the middle of 1943, were transferred to the control of a Base Defence Sector for training with Mosquito night fighter squadrons, which would also eventually come under the control of No. 85 (Base) Group to which the three BDSs were also allocated.

The five chosen landing beaches in Normandy, (codenamed Sword, Juno, Gold, Omaha and Utah) presented a wide front which could not easily be covered by a single mobile unit. Because of this, it was considered desirable to have two units to perform the defensive function and it was clearly sensible to place them at Juno and Omaha, the second and fourth beaches from whichever direction they were viewed. Accordingly, Juno Beach (which forms no part of this account) was allocated GCI 15083 from No. 24 BDS to cover Sword, Juno and Gold, and GCI 15082 from 21 BDS was planned to provide radar coverage on loan to the Americans who were responsible for Omaha and Utah beaches.

As D-Day approached, there must have been some misgivings among those planning the operation, regarding the success of the mission being achieved with the – then – allocated personnel. Accordingly, a number of additional specialists, which included a Radar Specialist and a Signals Specialist, a Padre, a Medical Officer and a number of other Trades, were added quite late in the day. These personnel would not have received the specific invasion training given to the earlier personnel who were to land on an enemy-held beach

The date of the planned invasion had been 5th June 1944 but, because of extremely bad weather causing difficult conditions in the English Channel, although the invasion did actually set off on the day planned, it was recalled before it had gone very far and was back in harbour within 3 hours.

The difficult decision was then made by General Eisenhower, the Commander-in-Chief, to begin the invasion 24 hours later than planned, when a slight window of better weather was forecast. Even so, sea conditions were still rough and most of the invading troops were very seasick. They had been on the assault vessels since 3rd June, vessels which were not equipped to provide basic facilities for eating, toilets, washing etc. and so they endured at least 3 full days cooped up in far from satisfactory ships.

Consequently, when the men from No. 21 BDS finally arrived offshore from the invasion beach at 11:00hrs high tide, what they did not want was to then spend another 6 hours on their flat-bottomed landing craft, going round in circles while Omaha beach was still not under American control, and while many of them were still suffering from seasickness!

The need for radar coverage was clearly considered to be vital and the decision was made by Officer Commanding Troops for them to land some 6 hours later than originally planned, even though the American troops were still not in full control of Omaha beach.

It had been planned for the GCI 15082 to land on the beach codenamed “Easy Red” near to the St Laurent exit from the beach. This section of beach had, in fact, been secured by the initial American assault troops and it is likely that a landing there would have enabled GCI 15082 to set up that evening, albeit somewhat later than planned. In the event and in the fog of battle, perhaps because of poor sea conditions and the shore also being obscured by smoke etc. from the naval bombardment, they actually landed on “Dog Red” section of Omaha beach near to the exit to the hamlet of Les Moulins.

Here the surviving remnants of the American 116th Infantry were still pinned down on the shingle rampart at the top of the beach. The German defences, both artillery and mortars, together with machine gun nests and snipers, still controlled the area. It was by now around 5.00pm and the tide was low, exposing far more of the beach. So, when GCI 15082 landed, some of the vehicles were immediately “drowned” when they drove into sunken bomb craters. Others made it to the high-water mark, but there was no way off the beach and these vehicles became sitting targets for the very accurate 88mm German artillery. Eventually, and with huge courage, a US bulldozer was commandeered and a path off the beach cleared, allowing the Section to make their way to the relative safety of the hamlet of Les Moulins.

To put into perspective the experiences of the two Mobile Radar Units that landed on D-Day, the Unit put ashore on Juno beach suffered no casualties to personnel and none of its equipment was damaged, enabling it to proceed to its previously selected site and be operational exactly as planned on the evening that it landed. By contrast, GCI 15082 of No. 21 Base Defence Sector, suffered 47 casualties during the landing, of whom 11 were killed in action, and they also lost all but eight of their 27 technical vehicles either to gunfire or “drowning” – and even these eight did not escape wholly unscathed.

As if all of the above was not enough for the men to endure, they became convinced that, not only were they being targeted by the German defenders, but they were also being fired upon by American troops! Apparently, the Americans had not been informed of the presence of this small Royal Air Force contingent. It has been reported that the intention was for all British troops to wear khaki battledress in order to avoid just such an eventuality, but very late in the planning stages it was decided that the RAF should retain their blue/grey uniforms. Unfortunately, by the time the troops had managed to get ashore through sea water, sand and other forms of dirt, their anti-gas sprayed blue/grey uniforms looked very similar at a distance to the field grey of the Wehrmacht. To the credit of the American commanders, this was quickly recognised, and they provided GI uniforms onto which the RAF personnel sewed their insignia and badges of rank, thus eliminating the risk of friendly fire.

Despite all these setbacks and trauma, with quickly supplied replacement equipment and personnel, the Unit was able to re-organise, set up its equipment and be operational (“on air”) on the night of 10th June. The determination of this Royal Air Force Unit to carry out its allotted task and the success that they achieved is illustrated by the number of successful interceptions the Mosquito Night Fighter crews thus achieved, “Destroying”, “Probably Destroying” or “Damaging” at least 87 enemy aircraft; by far the majority were destroyed. All this was achieved despite the dreadful experience of D-Day, and in the relatively short timespan of the 15 weeks that the Unit was based in Normandy.

Claims by Night Fighter Aircraft under the Control of No. 21 Sector

June to September 1944

(From Operations Record Books and Combat Reports)

GCI Station
























The account is drawn from both Official Records and also from personal memoirs written by men who took part in this undertaking.

It is not often that accounts of Royal Air Force operations involving ground-based airmen rather than aircrew are ever written. However, such is the drama, courage and resilience to be found in this landing that it is believed that more publicity is warranted in respect of this particular operation.

Not only did the survivors, who were scattered along the beach, manage to re-form and salvage eight of their vehicles which, though partially damaged, could be driven off the beach, but they also took delivery of replacement vehicles and personnel. These enabled the re-equipped GCI to set up, and be operational by the evening of 9th/10th June 1944 – and even manage to claim an enemy aircraft destroyed that night.

GCI 15082 eventually set up on a more permanent site near Grandcamps and settled into their prime task of detecting enemy aircraft approaching their designated area, and then vectoring Allied Night Fighters – DeHavilland Mosquitos fitted with Airborne Interception (AI) radar – to within a close distance from the enemy aircraft. From there, the Mosquito’s AI could pick up the contact, enabling the Navigator / Radar Operator to vector his pilot to a position where they could both positively identify the “bogey” as an enemy aircraft and destroy the intruder using the Mosquito’s four 20mm cannons.

The meritorious manner in which GCI 15082 recovered from its severe handling by the defending German troops on D-Day and then went on to carry out its task as planned can be appreciated by the later awards for their actions on D-Day of four Military Crosses to Officers of GCI 15082, two Military Medals to Other Ranks and the award of a Croix de Guerre to a Senior NCO.

What follows is their story during their relatively short but eventful time in Normandy.

2 Responses

  1. This is so incredibly moving to read the account of GCI unit 15082, especially seeing 47 casualties and 11 killed. “Despite all these setbacks and trauma, with quickly supplied replacement equipment and personnel, the Unit was able to re-organise, set up its equipment and be operational (“on air”) on the night of 10th June.”

    I’m starting out on my search to find out more about another GCI unit (15072), which my grandfather Robert Cox served in. No idea what the size of this unit would have been, but I’m beginning to think from the table above perhaps it was a much smaller GCI unit. He told my father that “he’d followed the Americans in on D-Day” and “had to borrow American top coats as worried that Americans would start shooting at us, thinking we were Germans”. I’m beginning to think that GCI 15072 were also on Omaha Beach on D-Day too.

    If anyone sees this comment and knows anything more, I can be reached at cox_sarah@hotmail.com

    Thank you

  2. My Father was on FDT 216 sited off Omaha & Utah, he may have been a radar operator but not certain, he was in the RAF also Combined Operations. I have looked online and searched many sites but still trying to add to the story he kept to himself until he was 85

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