"they (Sikhs) were the worst abusers of alcohol and opium"
- Defence of Europe by Sikh Soldiers in the World Wars By Mohindra S. Chowdhry · Published:2018 https://www.abebooks.co.uk/9781788037983/Defence-Europe-Sikh-Soldiers-World-1788037987/plp "Ranjeet Singh consumed alcohol and opium" Great Kings in The World By Manoj DoleOpium and tea
The roots of the Opium War (or First China War) lay in a trade dispute between the British and the Chinese Qing Dynasty. By the start of the 19th century, the trade in Chinese goods such as tea, silks and porcelain was extremely lucrative for British merchants. The problem was that the Chinese would not buy British products in return. They would only sell their goods in exchange for silver, and as a result large amounts of silver were leaving Britain.
In order to stop this, the East India Company and other British merchants began to smuggle Indian opium into China illegally, for which they demanded payment in silver. This was then used to buy tea and other goods. By 1839, opium sales to China paid for the entire tea trade.
https://www.nam.ac.uk/explore/opium-war-1839-1842