The primary country involved in the Opium Wars with China in the 19th century was Great Britain. The First Opium War occurred from 1839 to 1842, sparked largely by China's efforts to suppress the opium trade, which had devastating social and economic effects on its society. Britain, seeking to protect its lucrative opium sales and trade interests, clashed with Chinese forces. The conflict resulted in the Treaty of Nanking, which ceded Hong Kong to Britain and opened several ports for trade, significantly altering the balance of power in East Asia and furthering the decline of the Qing Dynasty.