The German Army sponsored a ballistic missile program in the late 1930s as a form of long-range artillery. The intention was to develop a weapon capable of delivering a one-ton payload to a range ten-times that of the World War I Paris gun, roughly 165 miles (270km). The A-4 missile program was officially initiated in 1936, but the technology was so radical that a series of sub-scale missiles had to be designed and tested before the full-scale missile could be developed. These experimental missiles were launched from a secret test facility at Peenemünde on an isolated peninsula in the Baltic starting in 1938. The first full-size A-4 missile was completed in February 1942 but the first attempted test launch in March 1942 failed. The fourth test flight, on October 3, 1942, finally succeeded, but the design was far from mature and test launches continued through 1943 to make the A-4 suitable for combat use. This missile is better known by its later propaganda designation as the V-2 (Vertgeltungswaffe-2: Retaliation weapon-2).
In the summer of 1942, the German Army sought Hitler’s approval to begin preparing for the mass-production of the A-4 missile, a major issue due to the enormous cost of the program, which was also likely to impact German aircraft production. The German generals promised that the new missile would succeed where the Luftwaffe had failed in the 1940 Battle of Britain. A storm of missiles would rain down on London, knocking Britain out of the war. Hitler had been ambivalent about the missile program, but the growing ferocity of British bomber missions over Germany changed his mind.
The FZG-76 cruise missile used a Walter steam catapult to get up enough speed for its Argus pulse-jet engine to ignite. This is an early test version of the launch system at the main experimental range at Peenemünde in the autumn of 1943. (NARA)
An early test example of the A-4 ballistic missile lifts off from Test Stand VII at Peenemünde in 1943. (NARA)
The Luftwaffe’s strategic bomber program had continued to stumble and there was little certainty that it would succeed. Although the Luftwaffe had rebuffed earlier attempts by aircraft companies to develop long-range strike missiles, the Army’s campaign to take away precious production resources to build their missile was enough to lead to a rival Luftwaffe missile program. Instead of a ballistic missile, the Luftwaffe selected a cruise missile design offered by Fieseler, the Fi-103. The Luftwaffe gave it the cover-name FZG-76 (Flakzielgerat 76), linking it to the innocuous Argus FZG-43 target drone. It would be better known in later years as the V-1. In contrast to the expensive A-4 ballistic missile, the FZG-76 was designed to be cheap to build and simple to operate, using a rudimentary pulse-jet engine and a small and simple airframe that could be manufactured by any aircraft plant. The design was so simple that test examples began to fly by October 1942. Hitler recognized that the FZG-76 program was an inexpensive alternative to the much riskier A-4 missile program, and both programs were allowed to continue in parallel through 1943.
Following the fall of France in 1940, the German Army deployed long-range artillery on the Pas-de-Calais to support the intended invasion of England. Although they could reach as far as some coastal cities such as Dover, they could not reach much beyond due to the limits of conventional artillery technology. In 1942, Eisenbahn-Artillerie Batterie 725 near Calais was assigned the task of testing a new extended-range rocket-assisted artillery projectile from one of its 280mm K5(e) guns that were intended to reach London. The test was a failure when the enormous propellant charge ripped the barrel apart. Although efforts continued to develop long-range projectiles, a more promising technology was also being explored by the Röchling plant, called the Hochdruckpumpe (HDP: high pressure pump), or Tausenfüßler (Millipede). Instead of using a single propellant charge at the breech of the gun, the pump gun used a sequence of smaller charges located in small chambers along the barrel’s 127m length. These were electrically fired as the projectile passed down the barrel, imparting energy more efficiently than a single charge. The aim was to develop a weapon capable of firing a 140kg projectile to a range of 165km. While this projectile was not as large as the warhead in a V-1 or V-2 missile, the presumption was that the low cost and volume of fire would make up for the relatively small payload. A sub-scale 20mm prototype was tested at a proving ground in Misdroy (now Miedzydroje, Poland) in April–May 1943, and the project attracted Hitler’s attention. In August 1943, he authorized the construction of a 50-gun HDP battery in France to supplement the missile campaign against London. This gun battery would have a theoretical rate of fire of one shot per tube every minute, or 600 rounds per hour, and 20,000 rounds per month. Although the rounds were much smaller than the missiles, the sheer volume of fire was enough to excite Hitler’s enthusiastic support. The full-scale prototype of the weapon was completed at the Wehrmacht’s Hillersleben artillery proving ground in October 1943.