Jay Smoker discovers that the drug was used to treat diarrhea back in the late 1880s:
When we dug deep down all the way back to 1886, we discovered a December edition of the Indian Medical Gazette which provides actual evidence on how cannabis is used to treat diarrhea. Dr. Turner, who worked at the Holloway Dispensary, came across a number of cases in which diarrhea was not only the main but also the underlying problem of many illnesses. He came up with a formula whose main component was cannabis. And it worked.
Cannabis also had a role in the Napoleonic Wars and the War of 1812:
For centuries, Russia was the world's largest producer of cannabis textiles. Despite Canada's growing number of cannabis farms and mills, in the early 1800's Britain's mighty navy was still mainly dependent on cannabis rope and sails made in Russia.
As Napoleon rose to power in France, Britain blockaded Europe with their superior navy, cutting the whole Continent off from Atlantic trade by controlling the English Channel and the Straits of Gibraltar. Unable to win at sea, Napoleon tried to beat Britain's navy by banning all European trade with Britain, to cut off their cannabis supply and isolate them economically. To get around the trade ban, Britain sometimes captured American ships and forced them to buy Russian cannabis and deliver it to England.
Russia didn't abide by the embargo for long, because the cannabis industry was too important to their economy. Napoleon needed to stop Britain's navy from getting their cannabis sails and ropes, so he launched his disastrous invasion of Russia in 1812.