The major impact of the 1st Opium War on China was the imposition of the Treaty of Nanking in 1842, which marked the beginning of a series of "Unequal Treaties" that favored Western powers. This conflict arose from China's efforts to restrict the opium trade, which was causing widespread addiction and societal issues. Defeated militarily by British forces, China was forced to cede Hong Kong to Britain, open several ports to foreign trade, and grant extraterritorial rights to foreigners. The war weakened the Qing dynasty, catalyzed internal strife, and contributed to a period of national humiliation, affecting China's sovereignty and paving the way for further foreign intervention.