The primary cause of the Opium Wars, which took place in the mid-19th century, was the trade of opium by British merchants in China. The Qing Dynasty attempted to suppress this trade due to its detrimental effects on Chinese society, including widespread addiction and social unrest. The British, seeking to protect their economic interests and trade routes, responded by using military force. The First Opium War (1839-1842) ended with the Treaty of Nanking, which favored British trade interests and humiliated China, while the Second Opium War (1856-1860) further entrenched foreign control over China’s trade and territorial integrity.