A wave of revolutions sweeps Europe, from France to the German states, Austria, Italy and Hungary, demanding democratic reform and national self-determination.
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.
Potato blight triggers a famine that kills about a million people and drives more than a million to emigrate from Ireland.
An alliance of the Ottoman Empire, Britain, France and Sardinia defeats Russia, with fighting centred on the siege of Sevastopol in Crimea.
The physician John Snow links a London cholera outbreak to a public water pump, a founding moment of modern epidemiology.
Britain and France fight Qing China, occupy Beijing and burn the Old Summer Palace in 1860, forcing further unequal treaties.
Louis Daguerre's photographic process is made public in France, the first commercially successful form of photography.