The First Opium War (1840- 1842) was a colonial aggression war launched by Britain against China. From the end of18th century, Britain smuggled a large amount of opium into China, which poisoned the people of China and caused a large outflow of silver from China. /kloc-at the end of 0/838, the Qing government sent Lin Zexu as an imperial envoy to Guangzhou to ban opium. 1June, 839, Lin Zexu ordered the public destruction of more than 2.3 million Jin of opium seized from illegal businessmen in Britain and the United States. 1840, Britain launched a war of aggression against China on the pretext of protecting trade. In the war, the Qing government wavered and compromised, and only a part of the army and the people stood up against the invaders together. In addition to harassing and occupying the coastal areas of Guangdong, Fujian and Zhejiang, the British army also captured Wusong, plunged into the Yangtze River, and pushed Nanjing, forcing the Qing government to sign the treaty of nanking in August 1842. Since then, China has gradually become a semi-colonial country.

Britain usually calls the first opium war "the first Sino-British war" (or "trade war"). Although this war is only a part of the Opium War, it is sometimes called the Opium War. The war has been going on intermittently, during which a series of battles and military actions are irrelevant.