Sausage ban fuelled Zeppelin drive
Germans were banned from eating sausages to help with the First World War effort, researchers have said.
Zeppelin airships were a key weapon for the Germans during the 1914 to 1918 war but production placed a huge demand on cow guts, used to make gas holding cells.
It took more than 250,000 cows to make a single airship and t he animals' intestines became so precious that making the popular bratwurst and other sausages was temporarily made illegal in areas under German control.
Details of the sausage ban were uncovered by researchers working on a Channel 4 documentary.
For the programme Dr Hugh Hunt, a University of Cambridge engineer, examined the role of the Zeppelin in the war, which foreshadowed the Blitz by bringing war to British civilians for the first time in centuries.
He studied how the silent aircraft were built and how the British adapted to their threat.
"One of the most intriguing things about the Zeppelins is that we don't have a huge amount of information about how they were built, nor about how they were destroyed," he said.
"But while shooting down a massive hydrogen balloon sounds pretty easy, actually it was quite the opposite.
"For the best part of two years, these things were able to fly over Britain, dropping bombs and causing havoc."
Records have long suggested that the Germans used cow intestines to contain the hydrogen needed to make them fly but it had never been clear how this was achieved.
Dr Hunt and his colleagues visited a sausage factory in Middlesbrough where they worked out that by making sausage skins wet, stretching them and allowing them to dry again, they could be bonded together to form ideal vessels for gas.
Conceived as a way to break British civilian morale, the Zeppelin raids never caused enough casualties to alter the course of the war.
But for civilians who witnessed them, the attacks, which began in January 1915, were a shocking experience.
London's East End and other towns in east and southern England, including Hull, King's Lynn and Great Yarmouth, were targeted.
Because of their stealth, the attacks were difficult to counter and when the raids ended in 1917, 77 of the 115 German airships had been shot down but 1,500 British citizens had been killed.
Dr Hunt said: " If you shoot a bullet at a balloon of hydrogen, all you get is a small hole.
"There were 50 thousand cubic metres of gas in a Zeppelin, and by putting a few holes in it, all you were doing was depriving it of a few cubic metres. It barely made any difference."
Eventually an incendiary bullet which set the Zeppelins alight was developed.
It was not until he began filming the show that Dr Hunt discovered the bullets' designer was his own great uncle, Jim Buckingham.
Attack Of The Zeppelins will be shown on Channel 4 on Monday.
Details of the use of cow intestines, or goldbeater's skins, were found in a document prepared for the US National Advisory Committee for Aeronautics in 1922. It details how the ban also applied to occupied Austria, Poland and Northern France.
It read: " The collection of the goldbeater's skins was very systematic in Germany during the war.
"Each butcher was required to deliver the ones from the animals he killed.
"Agents exercised strict control in Austria, Poland and Northern France, where it was forbidden to make sausages."