Modern Era
Treaty of Nanking (1842): The First of China's Unequal Treaties
China ceded Hong Kong Island, opened five ports, abolished the Cohong and paid 21 million dollars, beginning the era of unequal treaties.
Region
Europe
Modern Era
Thames Tunnel (1843): The Brunels' Tunnel Under a Tidal River
London gained the first tunnel known to have been built successfully under a navigable river; it later became part of the city's railway network.
Modern Era
SS Great Britain (1843): Brunel's Iron Screw Steamship
The first large iron-hulled, screw-propelled ocean steamship was launched; it later sailed for decades on the Australia route and survives as a museum ship in Bristol.
Modern Era
Great Irish Famine (1845-1852): The Potato Blight and Exodus
About one million people died and well over one million emigrated, and Ireland's population fell by roughly a quarter within a decade.
Modern Era
Joule's Paddle-Wheel Experiment (1845): Heat as Energy
Joule showed that a fixed amount of mechanical work always produces the same amount of heat, undermining the caloric theory and supporting the law of conservation of energy.
Modern Era
Repeal of the Corn Laws (1846): Free Trade and Peel's Fall
The Importation Act 1846 phased out duties on foreign grain by 1849, split the Conservative Party and brought down Peel's government.
Modern Era
Discovery of Neptune (1846): The Planet Found by Mathematics
Neptune became the first planet found by mathematical prediction rather than by chance, a striking confirmation of Newtonian gravitation.
Modern Era
Semmelweis and Handwashing (1847): Fighting Childbed Fever
Handwashing with chlorinated lime cut maternal deaths in the clinic dramatically, but Semmelweis's explanation was widely rejected during his lifetime.
Modern Era
Young Ireland Rebellion (1848): Rising During the Famine
The rising collapsed after a brief exchange of fire with police; its leaders were convicted of high treason and transported to Van Diemen's Land.
Modern Era
Frankfurt Parliament (1848-1849): First German National Assembly
The Assembly adopted a constitution for a united Germany in March 1849, but the King of Prussia refused the imperial crown and the parliament was dissolved.
Modern Era
Hungarian Revolution of 1848: Kossuth Against the Habsburgs
Hungary was defeated by Austria and Russia in August 1849 and ruled directly from Vienna, but the end of serfdom survived and the revolution became a national founding myth.
Modern Era
The Communist Manifesto (1848): Marx and Engels' Pamphlet
A small pamphlet with little impact in 1848 became, from the 1870s onwards, one of the most widely read and influential political texts in history.