Treaty of Nanking comes into effect, Hong Kong Island is ceded to the British "in perpetuity".

The Treaty of Nanking was a peace treaty which ended the First Opium War (1839–1842) between Great Britain and Qing Dynasty in China on 29 August 1842. It favoured British traders in treaty ports.

In the wake of China's military defeat, with British warships poised to attack Nanking, British and Chinese officials negotiated on board HMS Cornwallis anchored at the city. On 29 August, British representative Sir Henry Pottinger and Qing representatives Qiying, Yilibu, and Niu Jian signed the treaty, which consisted of thirteen articles. The treaty was ratified by the Daoguang Emperor on 27 October and Queen Victoria on 28 December. Ratification was exchanged in Hong Kong on 26 June 1843.