It was no secret that before WW2 the Germans were working on high energy fuels, explosives and rockets. The first reports started at the end of 1939. One was an anonymous letter to the British Naval Attaché in Oslo stating that the Germans were working on radio controlled flying bombs on the Baltic coast. Another was from the Polish Underground Army Intelligence saying that the Germans had set up a highly secret operation on a remote Baltic island, Usedom, and in the town of Peenemunde. In spite of this information the British scientists believed that there were no high energy fuels and high temperature materials available that would permit such weapons and, as a result, the reports were shelved.
One person who did take this information and threat seriously was R. V. Jones, the British Government Scientific Advisor. Knowing the reputation of Bletchley Park, he went there and briefed the intelligence section on the subject and asked for any Enigma intercepts that might throw light on the subject. Knowing the subject, they could now extract the pertinent information from many received and decrypted messages. One such superficially unimportant message, which had been previously decrypted and catalogued, concerned a German NCO from an Experimental Unit supporting beam bomber operation against Britain, who had been reassigned to Peenemunde. This was a very important and reliable confirmation of previous reports. A month after R. V. Jones' visit alerted Bletchley Park, intercepted messages indicated that the Germans were plotting the paths of flying objects over the Baltic Sea.
From the numerous data the British extrapolated the launch pad to be at Peenemunde. Further, the messages on missile tracking revealed its speed, flying height, and range. The final convincing argument came from an Enigma intercept that a special anti-aircraft unit was ordered for a location on the Baltic coast. Armed with that information R. V. Jones was able to make a presentation indicating the reliability of his data and accuracy of the weapon description. A few days later, an air reconnaissance mission brought photographs of Peenemunde showing a V1 on a launch pad and removing any remaining doubts about the purpose of this weapon. Due to the serious threat, that these weapons posed to Britain a massive air raid on Peenemunde, consisting of 600 heavy bombers, was ordered in August 1943. It was planned in absolute secrecy and even the bombing crews did not know what they were bombing. To achieve a total surprise a detachment of Mosquitoes was sent to Berlin to decoy German fighters from Peenemunde. The raid was led and controlled by Pathfinders who marked the target with coloured flares. As a result 130 German scientists and 600 foreign workers were killed and numerous sites levelled.
This action delayed experimentation and production by at least six months and eventually forced the Germans to move the operation to southeastern Poland, out of range of the Allied bombers. The British realising that the threat was imminent ordered massive bombing of V1 launch ramps found in France and on any suspected manufacturing plants. They also ordered an all out effort to obtain intelligence information on V1 and V2 rockets.
Polish intelligence operating in Poland was best equipped to do this. They were able to penetrate German security and recruit a worker to report on flying bomb construction, weight, type of engine, launch ramp construction and layout of Peenemunde buildings. Also a separate activity pertaining to the V2s that were landing in southeastern Poland was started. With a very large network of observers and strategically located couriers they were able to locate the V2 drop sites and collect the remaining parts before the Germans were able to do so.
On May 20th, 1944 they beat the Germans to some rather well preserved V2 remains, which they dumped into the nearby Bug river for later recovery. After collecting all the sighting and technical data they wrote a report that contained the following intelligence information:
General description of V2
Detailed technical description and operation of many internal units
Drawings of the launch sites and buildings at Blizna, number of launches and locations where the rockets landed
Names of German plants involved in manufacturing of the V2
Eighty photographs of various V2 parts
Twenty-five drawings of internal parts that could not be photographed.
Arrangements were made to send a DC3 Dakota plane to a landing site in Poland to pick up the report, the V2 parts and the intelligence man responsible for V2 intelligence gathering in Poland. It almost ended in total disaster as the aircraft wheels sank in the rain soaked landing field. It took over an hour to dislodge them so the aircraft could take off. All together more than 400 partisans took part in this landing operation and in securing the area against German attack. More than 140 partisans lost their lives in the V1 and V2 operations. Of more than 10,000 V1 launched, 7488 reached England, 3957 were destroyed and only 3531 reached London. More than six thousand civilians were killed and eighteen thousand were wounded. The 1150 V2 that landed in London killed 2,742 civilians and wounded 6467. The total property damage was 23,000 houses totally destroyed and 100,000 damaged while the RAF lost 490 aircraft.
Had not R. V. Jones believed in Bletchley Park the British would have found themselves being attacked by a very large number of V1 and V2. This would have caused major civilian and military losses and disruption of the invasion of the Continent. The day before the invasion Bletchley Park was on full alert to listen for and decrypt German Enigma messages for any hints that the Germans knew of the impending invasion. There was no sign of it until early in the morning of 6th June when an order was given to attack landing craft. This was too late to be of any use to the Germans. Both the Prime Minister and the Allied Commanders were briefed on the status of German Command orders.