What caused the First Opium war?

"The opium war arose from the conflict between China (Qing dynasty) and Britain when China attempted to stop the trade of Opium." (Pletcher)

British traders had been illegally exporting the drug from India to China. Ever since the trade grew dramatically, it caused enormous social and economical complications in China. Consequently, the Chinese Government destroyed around 1400 tons of Opium from British merchants. The situation escalated when British warships destroyed a blockage in Hong Kong. In 1840, an expeditionary force was sent to China and traveled to Hong Kong and northwards towards the Bei in order to urge China to listen to their demands. (Lewis) After advancing up the pearl river to Canton and months of negotiation, the British attacked, and the Qing forces were inferior to the British soldiers. Despite the Chinese counterattack in 1842, the British eventually won the war. The fighting finally ended in late August, when the troops captured Nanking.