I think this sums it up nicely. The History of Hemp by Derek Bielby The history of Hemp (Cannabis Sativa) provides a fascinating story going back more than 6,000 years. China has an unbroken history of Hemp textile production dating from 4,500 BC with the spread to Asia around 1,000 BC and reaching Europe around 800 BC. It became an important crop of enormous economic and social value supplying much of the world's need for food and bast fiber. Sailing ships became dependent on Canvas (from the word cannabis), hemp rope and oakum due to it being 3 times stronger than Cotton and rot resistant to salt water. In 1175 Hemp was taxed and in 1535 Henry VIII passed an act compelling all landowners to sow 1/4 of an acre, or be fined. During this period Hemp was a major crop and up to the 1920's 80% of clothing was made from Hemp textiles. The biggest decline for the U.K. fibers came from Cotton, and with the advent of the 'Spinning Jenny' in the 1970's Cotton prices fell dramatically. A further crisis for Hemp arose in America during the 1930's due to propaganda created from companies with vested interest from the new petroleum based synthetic textile companies and the large and powerful newspaper / lumber barons who saw Hemp as the biggest threat to their businesses. Traditionally, Hemp was processed by hand which was very labor intensive and costly, not lending itself towards modern commercial production. In 1917 American George W. Schlichten patented a new machine for separating the fiber from the internal woody core ('Hurds') reducing labor costs by a factor of 100 and increasing fiber yield by a factor of 60. Mr Schlichten and his machines disappeared, not surprisingly! During the Second World War the supplies of Hemp from the East were being cut off so American farmers were encouraged to grow Hemp for military use (webbing, canvas etc.) under the banner of "Hemp For Victory". After the war, licenses were subsequently revoked, at a similar time to the last Hemp crops being grown in the U.K. In 1971 Cannabis became caught up in the politics of the Opiate laws and became classed as a restricted plant under the misuse of drugs act. In the 1990's new agricultural initiatives were put forward in Europe towards sustainable alternative crops to alleviate the massive surpluses of food being produced. Farmers in the U.K. felt disadvantaged and lobbied the Home Office into harmonizing legislation across the EC. In 1992 / 93 the first licenses were granted for growing Hemp of the low THC varieties (THC is the narcotic substance found in the plants leaves) under the ruling that Hemp is grown for "special purposes" or "in the public interest". http://www.hemp-union.karoo.net/main/info/history/book1.htm