Two Royal Air Force Mobile Radar Units landed in Normandy on 6 June 1944 but their experiences could not have been more different.  GCI 15083 which belonged to No.24 Base Defence Sector (BDS) landed on time on Juno Beach with no losses of either personnel or vehicles and was able to set up at its appointed position and be operating on the evening of 6/7 June 1944.  In complete contrast, GCI 15082 of No. 21 BDS set out to land on Omaha Beach at its appointed time of 11.00 hours, (high tide), but was called off because of the dire situation on the beach and spent the next 6 hours circling several miles off the beach in the choppy waters of the Channel.

Eventually, such was the importance given to getting mobile radar onto the beach the ‘Officer i/c Troops’ ordered GCI 15082 to land anyway. Sadly, this decision resulted in the dreadful results described elsewhere on this website. It is possible that there was nothing wrong with the order but everything wrong about its execution. Beach draw E-1 was opened up by 4.30 pm and a semblance of order was being established there. (Draws are similar to valleys on a smaller scale; however, while valleys are by nature parallel to a ridge line, a draw is perpendicular to the ridge, and rises with the surrounding ground, disappearing up-slope.) It is known how determined the planners were in wanting the GCI to be ashore as early as possible, and so it may well have been a calculated risk in diverting GCI 15082 from their original landing site to the recently opened draw. Tragically as we know, the actual landing site was 1,200 metres to the West and was far from open. Perhaps the order to land was received but not the new location, or maybe errors in navigation led to the disaster. We will probably never know what actually happened.

Even though a report was submitted via the Operations Record Book (ORB) of 21 BDS, it does not identify the person/persons who gave the order.  We must assume that, as the planners of the landings had decided that two reasonably sized, non-combatant, ground-based technical Royal Air Force units had to be in Normandy at the very outset, their presence was considered vital.  What this urgent need was, is addressed elsewhere on the website (see Section Research; D-Day: Its organisation; Fighter Direction Tenders) but in order to try to understand why GCI 15082 was ordered to land despite the beach not having been secured nor some of the exits having been cleared, and with the beach itself littered with destroyed equipment and many dead and dying assault troops, we need to know what their task was.  In short, it was to detect approaching, potentially hostile aircraft and vector a patrolling Mosquito Night Fighter to intercept it.  The aim was to get the night fighter closer than 8 miles to the incoming aircraft so that the onboard Airborne Interception radar (AI) could be used by the second crewman to take over the task of guiding his pilot to intercept from the rear of the suspected enemy aircraft, slightly below and to the side so that a visual identification could be made by both crew aided by the Ross night vision binoculars used by the radar operator.  Once the aircraft had been confirmed as hostile by both crew members, the pilot then throttled back slightly so as not to be too close to the enemy aircraft (e/a) when he opened fire since the e/a potentially exploding could and did occasionally damage the attacking night fighters.  After the on-board AI had taken over, the ground based mobile radar unit often continued ‘watching’ the unfolding events and could, where necessary, redirect the night fighter if the e/a had managed to elude the first attack or to confirm the exact position of the combat. 

Such was the importance of this task, that the land-based GCI units were expected and indeed, were risked to complete this task. The potential risk to the thousands of men and tonnes of material holed up on the beach and near hinterland resulted in the planners requesting the mobile RAF units to land at the very earliest possible time.

The success of this co-operation between the Mobile Radar Units and the Mosquito night fighters can be judged by the number of enemy aircraft which were destroyed between D-Day and the beginning of February, a congratulatory signal from 85 (Base) Group giving the number as 250.

On 23 August 1944, GCI 15082 was ordered to move from its established base near Grandcamps to Paris in order to provide radar coverage over Paris as the Allies approached the city.  Even though 21 Sector had another 4 such units available and 24 Sector had 5, the chosen unit was the one which had received its baptism of fire on Omaha Beach.  Accounts by some of the men who were with GCI 15082 at this time claim that it was the first Allied unit of any description to enter Paris!  Whatever the truth of this claim, they were certainly among the very first to enter Paris when it was liberated.

By the middle of August, the American Forces had their own MEW (Microwave Early Warning) radar available.  However, the 4 GCIs belonging to 21 Sector, including GCI 15082, were not embarked until almost the end of September 1944 and returned to England via Utah beach in seven Landing Craft.  They disembarked in Southampton and proceeded to RAF Ibsley where, after a short spell waiting for orders, the Unit’s establishment was cancelled, and the personnel were posted elsewhere.  The 5th MRU was transferred to 24 Sector and remained on the Continent and the attached Mobile Signals Units were deployed elsewhere in Europe.

As an indicator of just how effective was the cooperation between the Ground Controlled Interception radar units of No.85 (Base) Group and their six allotted squadrons of Mosquito night fighters, the following figures give an indication of this:

a)       Results claimed between 6 June 1944 until 31 January 1945