The Second Opium War (simplified Chinese: 第二次鸦片战争; traditional Chinese: 第二次鴉片戰爭), also known as the Second Anglo-Chinese War or Arrow War, was fought between the United Kingdom and France against the Qing dynasty of China between 1856 and 1860. It was the second major conflict in the Opium Wars, which were fought over the right to import opium to China, and resulted in a second defeat for the Qing and the forced legalisation of the opium trade. It caused many Chinese officials to believe that conflicts with the Western powers were no longer traditional wars, but part of a looming national crisis.
On 8 October 1856, Qing officials seized the Arrow, a British-registered cargo ship, and arrested its Chinese sailors. The British consul, Harry Parkes, protested, upon which the viceroy of Liangguang, Ye Mingchen, delivered most of the sailors to the British on 22 October, but refused to release the rest. The next day, British gunboats shelled the city of Canton. The British government decided to seek redress from China and dispatched a naval force led by Michael Seymour, and France joined in the action, citing as its reason the murder of a French missionary in China. After coordination with each other, the British and French stormed Canton in December 1857. Ye was captured and the governor of Guangdong surrendered. The alliance then moved north to demand a treaty from the Qing court, and on 20 May 1858, captured the Taku Forts, stormed Tianjin, and threatened the capital Beijing. The Qing asked for peace, and signed the Treaty of Tientsin with Great Britain and France in 1858.