The Opium War between China and Great Britain was during 1839-1842. Opium is a drug grown in India and is used to make morphine and heroin. It is used to relieve pain, but it can also be harmful. The British decided that they needed to balance their trade so they decided to sell and buy this drug to China. China didn't like that, so they decided to put, whoever is dealing with Opium, to death. The Chinese wanted to stop the growing import trade in Opium. Obviously, the medicine wasn't doing any good, it turned into a drug. The tradings began to flourish. The British Opium trade started in China and began the world's first drug war.
By the middle of 1842, the British had defeated the Chinese at their trade route, the Yangtze, and were occupying Shanghai. The war finally ended in August 1842, with the signing of China's first Unequal Treaty, the Treaty of Nanking.