1850s

The 1850s decade ran from January 1, 1850, to December 31, 1859.

Wars

Crimean War (1854–56) fought between Imperial Russia and an alliance consisting of the United Kingdom of Great Britain and Ireland, the Second French Empire, the Kingdom of Sardinia and the Ottoman Empire. The majority of the conflict takes place around Crimea, on the northern coasts of the Black Sea.
On 8 October 1856, the Second Opium War between several western powers and China begins with the Arrow Incident on the Pearl River.
Second War of Italian Independence (1859), also known as Franco-Austrian War, or Austro-Sardinian War.

The Indian Mutiny: revolt against British colonial rule in India
Bleeding Kansas (1854–59): battles erupt in Kansas Territory between proslavery and "Free-State" settlers, directly precipitating the American Civil War.
Taiping Rebellion (1851–64) in Qing China.

The 1850s were marked by several notable assassinations and assassination attempts:

Eight were killed and 142 wounded in Paris in a failed assassination attempt on Napoleon III, Emperor of the French (1858).

Charles Darwin publishes The Origin of Species, putting forward the theory of evolution by natural selection in 1859
Epidemiology begins when John Snow traces the source of an outbreak of cholera in London to a contaminated water pump.
Discovery of Neanderthal fossils in Neanderthal, Germany
Solar flares discovered by Richard Christopher Carrington

Distinction between coats and jackets begins to blur
Production of steel revolutionized by invention of the Bessemer process
Benjamin Silliman fractionates petroleum by distillation for the first time
First transpacific telegraph cable laid
First safety elevator installed by Elisha Otis
Railroads begin to supplant canals in the United States as a primary means of transporting goods.
First commercially successful sewing machine made by Isaac Singer

Kate Chopin was born. Nikola Tesla