Operation Crossbow was the codename for a vital military operation to find V1 and V2 bases in northern Europe, primarily in north France. Operation Crossbow was centred at RAF Medmenham, 60 miles to the west of London. It was at Medmenham that RAF personnel interpreted reconnaissance photographs and passed on their findings to higher authorities.
The whole topic of photographic reconnaissance started with the pilots who flew over occupied Europe seeking out anything that might indicate that the Nazis were doing something different – moving troops, moving barges etc. In particular the pilots were on the lookout for new buildings or building sites.
Reconnaissance pilots flew modified Spitfires that were high powered but unarmed, thus reducing their weight and increasing their speed. The Spitfires were fitted with five powerful cameras that throughout the war took many millions of photographs. They were painted a grey-blue colour so that they blended in with the sky, as their optimum flight height was 30,000 feet. If by chance they were attacked, it was generally considered that the Spitfires had the necessary speed to escape any attacker – up to the introduction of the ME-262 jet fighter.
Once a reconnaissance Spitfire had landed, the cameras were taken off and the stills processed and studied. The photographs were put into three categories depending on whether they were of value. They were studied by photographic interpreters (PI’s) at RAF Medmenham and it was up to the PI’s as to what category each photograph went into.
If something on a photo was deemed to be of great interest, a reconnaissance flight was ordered to where the original was taken so that a more detailed collection of photographs could be taken. Here pilots were required to fly level on a specific set of coordinates so that they gained a perfect set of images that were not blurred. More important, the coordinates they flew on meant that they had images that overlapped. These overlapping images allowed the PI’s to build up what was effectively a 3D image of what it was that had interested them in the first place. These types of images gave accurate heights and widths – both vital in trying to work out what exactly the image was.
The campaign against the V1 and V2’s started when an inquisitive pilot noticed what to him were odd buildings and curious shapes on the ground at a place called Peenemünde, which up to that time was unknown to British intelligence. The photographs showed many new buildings and three curious large circular shapes on the ground. The images baffled the PI’s as they had nothing to compare them to. However, these images were the first the British had of the rocket testing facility in northern Germany. The work done by the PI’s at RAF Mendenham led to a major attack on Peenemünde on August 17th/18th 1943.
The approach of D-Day focussed the minds of most in the Allied forces. However, PI’s remained concerned as to what the Peenemünde images represented. French resistance information had also told British intelligence of a number of newly built complexes or building projects near to the north French coast. These were investigated by the reconnaissance pilots. They brought back many odd images. Rather than having to fly at 30,000 feet, these missions required the pilots to do the opposite – fly in at a very low level that put them in danger of anti-aircraft gunfire. The intensity of the fire they met convinced the pilots that what they were photographing were of great importance to the Nazis. What baffled the PI’s were odd structures that appeared to be ski ramps on their sides – the nickname ‘ski ramp’ stuck. In fact, they were the storage shelters for the V1’s, which were first used against London just days after June 6th 1944 – D-Day.
The first use of the V1’s made the work of the pilots and the PI’s even more important. 3D imaging allowed the PI’s to identify the storage facilities and the actual ramps used to launch the V1’s. PI’s had become so good at their job that they even recognised the scorching of the earth by the flame that each V1 gave off as it was launched. This information was vital and passed on to Bomber Command or the USAAF who launched massive bombing raids against what were in essence small targets. However, the impact of the raids meant that the V1 units were forever on the move. Combined with better home defences, such raids made the V1 far less destructive than it may have been.
The V2 was also identified by the PI’s at 3D level but because it was a weapon that could be moved and was invariably launched in woodland, bombing raids would not work. Peenemünde had been bombed but this resulted in the factories being rebuilt inside the mountains near Nördhausen where they were safe from bombing. The threat from the V2’s remained until Nördhausen was overrun by the Americans. It was only then that the brutality behind the V2 was observed as the labourers at Nördhausen came from the nearby Dora concentration camp. Thousands of inmates died within the Nördhausen complex.
There can be no doubt that the work done by the reconnaissance pilots and the PI’s was vital to the war effort. The success of ‘Operation Crossbow’ helped to ensure that D-Day itself was a success as no one knew if the V1’s could be targeted at ships in mid-Channel. While hitting a moving object at sea would have been a matter of luck, the probable panic that would have ensued may well have thrown the actual landings into disarray. As fanciful as it may have seemed to some, the risk simply could not be taken. The PI’s identification of the launch sites of the V1’s was of great importance to the commanders of D-Day – as was their destruction. It would have been a view shared by the people of London and southeast England.