Hermann Oberth's Die Rakete zu den Planetenräume (The Rocket Into Interpanetary Space) was published at the very end of 1923. The book made it clear to young German engineers that manned flight into outer space was achievable. It was only necessary to develop the technology!
The first German rocket craze ran from 1928 to 1933. Impatient German enthusiasts such as Opel, Valier, and Tiling demonstrated everything from motorcycles to aircraft powered by existing black powder rockets. Quacks like Zucker capitalised on the craze by equipping large hulls with powder rockets and making outlandish performance claims. Powder rockets were used to send letters from town to town, and 'rocket post' became sought after by philatelists. But the performance of the black powder rocket was so poor that it was evident that they could never be used to reach space.
To those seriously interested in reaching other planets within their lifetimes, it seemed that development of the liquid rocket engine was necessary to build space ships. This would require collaborative effort. In June 1927 Johannes Winkler called to order in Breslau the first meeting of the world's first Society for Space Travel (Verein fuer Raumschiffahrt or VfR). The membership grew from three to 500 within the year. Willy Ley was instrumental in publicising the Society and editing its newsletter.
The space craze caught the attention of the Ufa film studio. Famed director Fritz Lang began production of the first film to realistically portray spaceflight - Die Frau im Mond (The Woman in the Moon). Lang turned to Oberth for technical advice, and gave Oberth funding to build and fly a working liquid propellant rocket before the film's premiere. However Oberth was a theoretician, not a practical engineer, and vastly underestimated the task. He fled the capital in panic when he realized that his rocket could not be made to work in time for the film's premiere on 15 October 1929.
Oberth's assistant, Nebel, proposed to use the rocket engine developed for the film as the basis for a 'Mirak' - a Minimum Rocket - that would fly and demonstrate liquid rocket technology to the public. In September 1930 Nebel was able to obtain use of an abandoned German army munitions storage area in a northern suburb of Berlin for use as a Raketenflugplatz - the world's first rocketport. Riedel, the most talented engineer of the VfR 'Berlin Group', worked feverishly to perfect the Oberth engine. But it was Winkler, heading the 'Breslau Group', who flew the HW-1, the first liquid propelled rocket in Germany, in February 1931. Riedel's Mirak Repulsor flew three months later. In parallel with all of this a Hannover Group, headed by Puellenberg, began development of refined liquid propellant rockets.
But events were already conspiring against the rocket enthusiasts. The stock market crash of 1929 had dried up funding from wealthy benefactors. Valier and Tiling were killed in accidents in their laboratories. In 1930 a Colonel Dornberger of the German Army was directed to pursue research into the rocket as a weapon of war from a proving ground at Kummersdorf. An enthusiastic young engineer of the Berlin Group, Wernher Von Braun, was recruited by Dornberger, and in the economic depression many of the other VfR engineers went with him. Nebel, Winkler, and Tiling continued independent work until the end of the summer of 1933. But then the new Nazi government ordered out the Gestapo to shut down all private rocket development in Germany. Only Puellenberg continued development in secret, until finally giving up in 1938.
It took von Braun's German Army team nine years to develop the primitive Mirak thorugh the A1, A2, A3, and A5 into the world's first long range ballistic missile, the A4 - V-2. After the war, groups of German engineers were recruited to transfer the technology to the winning allies. Von Braun and 107 engineers went to American; Groettrup and 307 others to Russia; Bringer and 29 others to France.
Back in occupied Germany, Nebel, Puellenberg, and Staats began renewed work on private rocketry. They formed a new rocket society, and got the Allied ban on German rocket tests lifted in 1952. A new rocketport was founded at Cuxhaven, on the North Sea coast. A new generation of private German rocket enthusiasts flew rockets (with those of Seliger reaching 120 km altitude) from Cuxhaven until 1964. Then Zucker, the old nemesis of the serious racketeers, managed to kill a boy in one his rocket tests. This led once again to the prohibition of further private serious rocket research in Germany again.