Nazi Germany tested its deadly V-2 rocket by firing it at its own cities, according to top-secret SS documents that recently came to light.
Thousands of Germans died in the 1944 and 1945 test firings, which were blamed on Allied bombing raids, according to the Mail Online website, which revealed the existence of the documents.
V-2 rockets went on to kill over 7,000 people when fired at southern England and northern Europe in the last months of World War II.
The 20-page archive is made up of V-2 project reports that were only issued to 'Kommandostelle S', a unit so secret that hardly anything is known about it.
An attempt was made to burn them at the end of the year, but they were rescued and have remained in the possession of a German collector ever since. They are due to be sold at an auction in London on March 18.
"A note which comes with the archive from a researcher indicates that these were final test firing reports for the rockets and were issued in very limited numbers of no more than 10 to 12 copies," said Richard Westwood-Brookes, spokesman for Chiswick Auctions, in London.
"The present archive could prove to be a highly important new source of information on what was by far the most important technological and scientific development to have come from the Second World War."
The reports indicate that a large number of V-2 rockets were fired from the Peenemunde region, where the experimental devices were developed and tested.
Shockingly, the reports reveal that before the rockets were fired at London, Antwerp and Liege, they were test-fired at German towns and cities - mainly in the area of Pomerania.
It is believed special units were then sent to evaluate the extent of the damage caused and report back to the Fuhrer about their effectiveness.
Many of the test firings at German towns and cities resulted in considerable casualties and substantial damages to houses and other properties.
After the war, the majority of V-2-related documents were destroyed by order of the SS before the Allies moved in.
"The fact that several of the sheets in the present archive have clearly been in a fire suggests that these very papers were rescued from such destruction," Westwood-Brookes said.