Representatives of the British Crown and many Māori chiefs signed the Treaty of Waitangi, New Zealand's founding document; differences between its English and Māori texts remain debated.
Britain wars with Qing China after it cracks down on the opium trade; the defeat opens what China calls the 'century of humiliation'.
The Qing cede Hong Kong Island to Britain and open five treaty ports, the first of China's unequal treaties.
Victoria succeeds to the British throne; her reign of more than 63 years coincides with the height of the British Empire.
Potato blight triggers a famine that kills about a million people and drives more than a million to emigrate from Ireland.
A series of armed conflicts between the colonial government and Māori iwi, chiefly over land and sovereignty, which led to large confiscations of Māori land.
Karl Marx and Friedrich Engels publish in London a pamphlet setting out the theory of class struggle, one of the most influential political texts ever written.