24th January » Political and state union of Moldavia and Wallachia; Alexandru Ioan Cuza is elected as Domnitor in both United Principalities called Principalities.
4th February » The Codex Sinaiticus is discovered in Egypt.
5th February » Wallachia and Moldavia are united under Alexander John Cuza as the Danubian Principalities e.g United Principalities, an autonomous region within the Ottoman Empire, which ushered the birth of the modern Romanian state.
14th February » Oregon is admitted as the 33rd U.S. state.
19th February » Daniel E. Sickles, a New York Congressman, is acquitted of murder on grounds of temporary insanity. This is the first time this defense is successfully used in the United States.
25th April » British and French engineers break ground for the Suez Canal.
4th May » The Cornwall Railway opens across the Royal Albert Bridge linking the counties of Devon and Cornwall in England.
31st May » The clock tower at the Palace of Westminster called Houses of Parliament, which houses Big Ben, starts keeping time.
4th June » Second Italian War of Independence named Italian Independence wars: In the Battle of Magenta, the France or French army, under Louis-Napoleon, defeat the Austrian army.
6th June » Australia: Queensland is established as a separate crown colony named colony from New South Wales (Queensland Day).
15th June » Pig War: Ambiguity in the Oregon Treaty leads to the "Northwestern Boundary Dispute" between United States and United Kingdom e.g British/Canada e.g Canadian settlers.
18th June » First ascent of Aletschhorn, second summit of the Bernese Alps.
24th June » Battle of Solferino (Battle of the Three Sovereigns): Sardinia and France defeat Austria in Solferino, northern Italy.
28th June » The first Conformation show called conformation dog show is held in Newcastle-upon-Tyne, England.
8th July » King Charles XV of Sweden known as Charles XV & IV accedes to the throne of Union between Sweden and Norway called Sweden–Norway.
30th July » First ascent of Grand Combin, one of the highest summits in the Alps.
16th August » The Tuscan National Assembly formally deposes the House of Lorraine called House of Habsburg-Lorraine.
2nd September » A Aurora (astronomy) Auroral events of historical significance e.g solar super storm affects electrical telegraph service.
17th September » Joshua A. Norton declares himself "Norton I, Emperor of the United States."
26th October » The Royal Charter (ship) named Royal Charter is wrecked on the coast of Anglesey, north Wales with 459 dead.
1st November » The current Cape Lookout (North Carolina) Cape Lookout, North Carolina, lighthouse is lit for the first time. Its first-order Fresnel lens can be seen for about convert 19 mi km in good conditions.
15th November » The first Zappas Olympics or modern revival of the Olympic Games takes place in Athens, Greece.
24th November » Charles Darwin publishes 'On the Origin of Species', the anniversary of which is sometimes called "Evolution Day"