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

The Treaty of Nanking was the peace treaty which ended the First Opium War (1839–1842) between Great Britain and the Qing dynasty of China on 29 August 1842. It was the first of what the Chinese later termed the "unequal treaties".

Hong Kong Island is an island in the southern part of Hong Kong. The island, known originally and on road signs simply as "Hong Kong", had a population of 1,289,500 and a population density of 16,390 per square kilometre (42,400/sq mi), as of 2023. It is the second largest island in Hong Kong, with the largest being Lantau Island. Hong Kong Island forms one of the three areas of Hong Kong, with the other two being Kowloon and the New Territories.