The war to promote cannabis

Cannabis is nowadays mostly viewed as a forbidden drug, but in the 19th century cannabis was a respectable fibre producer.
Dutch Cannabis (or hemp) never grew popular, as the soil was deemed not suitable for large cultivation areas. It has been cultivated mainly in some minor valley peat areas in the south of Holland, such as the Alblasserwaard.
Staring (1862) estimated the total of hemp culture at 1324 hectares, of which 1157 in the Zuid-Holland province. But even then, these 1157 hectares were a mere 2% of the total agricultural area.
More extensive hemp culture has been promoted in several pamphlets, but none of these were truly successful. Still, Cannabis culture had its typical ups and downs in the meantime, before a decline at the end of the 19th century.
Verrips (1978) offers a nice explanation about the final decline of hemp culture: hemp culture has its most intensive period of manual work in exactly the same periods as diary farming, which was the most important subsistence method of the Dutch farmers. As prices of meat and diary products rose in the later 1800's (mostly because of foreign demand), farmers (who earlier still balanced between cattle and hemp) decided against the fibres. Besides, fibre demand had weakened because of cheap foreign imports.
These foreign imports had various reasons, but partly came from a combination of low grain prices and war threats around the Baltic Sea. War gave a boost to the rope and sail industry, which was the main use for hemp.
From comments in Kok's 'Vaderlandsch Woordenboek', it seems that also in Baltic countries, farmers switched between cultures (in this case grain and hemp), and that hemp served as a compensating trade in times when grain prices were low. The Baltic grain trade has been extensively researched in van Tielhof's book (2002), and it would be interesting to investigate whether the hemp trade was indeed anticyclical to the grain prices.
Though it must be noted that exact data for hemp culture are sometimes diluted by the fact that in older literature the term 'linen' is used for both cloth of flax and hemp origin.

Dutch technical literature neglected knowledge on hemp for long, and the main treatise on hemp, that of the French Duhamel du Monceau (first published 1747), was never translated into Dutch. Not because of ignorance: several other treatises by du Monceau did get published in the 'Volledige beschrijving van alle konsten', published by Blussé from 1788 to 1820. But as hemp was a minor culture and the Netherlands were mainly depending on imports, it was probably felt that an practical instruction was not needed.

Napoleontic wartime needs, however, made way for the first promotional brochure, 'Onderrigting wegens de hennip-teelt in Holland', somewhere between 1810 and 1813. As the first page states: 'Voor het zeewezen is hiervan eene groote voorraad noodig, en het is te wenschen, dat wij den Hennip telen op onzen eigen grond'. During the last twenty years, the brochure states, prices for hemp had more than doubled (that is, shortly after the French revolution, and a period of continuous tumult started), making the trade highly profitable at that moment.
During the same period, the last phase of Napoleontic rule, an article described the culture du chanvre dans le royaume des Pays-Bas as steady, but important.
Of course, 'important' was relative: at the end of the imperial era, homegrown hemp literally represented a lifeline for the fighting marine ships.



After 1813 and the return of Willem I as king things around hemp became more quiet again. The Groningen professor Van Hall provided a new booklet in 1830, but for a different reason. He was trying to promote a more diverse cycle of cultures. The high input necessary of manual labour for the retting, however, still made it hard for farmers to start growing hemp.
Retting still is a hard and intensive method in modern times, and in the 19th century, retting was even more a breakpoint for the fledgling fibre industrialization.
In the meantime, the French engineer Christian had developed a machine for processing hemp (and flax) without retting, Christian enthusiastically published a promotional brochure in several languages, called in Dutch 'Handleiding voor landlieden over de wijze om vlas en hennep zonder roting te bereiden', with six folding plates copied from the French edition. Practical testing by others, however, proved the machine to produce too much short fibre fragments. Long fibres are wanted for more sturdy and durable fabric, and the machine never became a success. The Dutch booklet version had an imprint in Brussels, but this was surely targeted at the then abundant flax culture in Flanders.
Similar annunciations of new methods were indeed also published for flax, but, as in hemp, retting remained the favored method of separating the fibres from the raw crop.