The main cause of the Opium Wars between Britain and China was the trade imbalance created by Britain's opium exports to China. In the early 19th century, British traders began selling opium, grown in British-controlled India, to Chinese consumers. This led to widespread addiction and social issues in China, prompting the Qing government to take action against the trade. Their efforts to suppress opium imports, including the confiscation and destruction of opium stocks in 1839, escalated tensions. The resulting First Opium War (1839-1842) ended with China's defeat and the signing of the Treaty of Nanking, which favored British trade interests and expanded Britain's influence in Asia.