The Opium Wars.

The British trades of opium with China started the world's very first drug war. Opium is a preparation made from the juice of poppy seedpods - used to produce heroine. This drug was very highly addictive, and many Chinese citizens were hooked on it. Before long, opium was becoming s big problem in China. Roughly 10% of the Chinese population was addicted to opium. It became a health factor, and it effected their economy. China later prohibited opium, but the British still brought it into the country. China actually accepted bribes from the British.
China was threatening to end ALL trades with Britain. After all, they were an isolated country. But the British didn't want it to end. The only thing they could think of was war. China started an anti-opium campaign, and the British wanted it to end. In 1840, British gunboats attacked the coastline of China. Also, China was behind when it came to modern weapons. Eventually, China was defeated, and was forced to sign the Treaty of Nanjing; which held the Chinese government responsible for all of the opium destroyed during the anti-opium campaign. Basically, the British won the war; mainly because of their advanced weapons and surprise attack. China was unprepared for the war, therefore they lost.