Just like all the other major construction works forming the Atlantic Wall, but with the added curiosity of being situated right in the centre of the future Anglo-American landing zone, the Longues guns were the target of several aerial reconnaissance missions. For such hazardous investigative missions, the British used very rapid planes, capable of flying at high altitude (30,000 ft), such as Spitfires or Mosquitos equipped with a narrow-angle lens camera. Thanks to periodical coverage of the coast, the Allied Staff was able to keep up with the Atlantic Wall's advancement. The two following pictures, taken by the RAF just before the D-Day landings, are an excellent example of the quantity and the accuracy of information offered by aerial reconnaissance, which proved to be the primary source of information to the allies during the final conflict. On the aerial photograph dated the 2nd of March 1944, in the lower right-hand corner, can be seen a few of the village houses surrounded by planted fields. Between the village and the cliff-top that overhangs the Channel, it is clear that, three months before Operation Overlord was launched, the construction of the coastal artillery battery had barely commenced. Three roads had been traced across the parcels of cultivated land for public works vehicles and lorries. Two major excavation sites, both destined to house a casemate, are perfectly visible on the road parallel to the coast. Other construction sites, of a smaller scale apart from the firing command post on the cliff-top, can also be seen on this exceptionally clear picture. On the second photograph, taken on the 22nd of May at low tide, the Longues construction site had taken on a totally new look. Roads, large and small concrete constructions and zigzagging networks of trenches had proliferated. The artillery position now resembles a genuine little fortress. With a magnifying glass, one can clearly distinguish the four firing casemates hidden, as was the Todt Organisation's custom, under huge camouflage nets hung over wooden stakes. It would appear that only German companies were involved in the construction of Longues, which was originally a Kriegsmarine coastal artillery battery which was to be retroceded to the Land Army shortly before the D-day landings. The German firms benefited from manpower comprising prisoners of war and forced labourers from Eastern Europe. Comparison between the two pictures brings to light the extraordinary efficacy of the Todt Organisation, made possible by the excessive standardisation of the concrete elements and the abundant, unrelenting and totally free manpower.