Denmark-Norway

State · 1526–1940 CE · at its largest around 1626 CE

The union of the kingdoms of Denmark and Norway under the Oldenburg dynasty, governed from Copenhagen, which also included Iceland, Greenland and the Faroe Islands, until Norway was ceded to Sweden in 1814.

On its lands while it lasted

Hanseatic trade route (1356–1669 CE): The Hanseatic League of north German merchant towns, led by Lübeck, dominated Baltic and North Sea trade from London and Bruges to Novgorod, exchanging furs, wax, grain, fish and timber for cloth and salt.
Nicolaus Copernicus (1473 CE – 1543 CE): Polish astronomer and canon of Frombork in Royal Prussia who proposed a Sun-centred model of the universe in De revolutionibus orbium coelestium, published in 1543, the year of his death.
Copernican heliocentrism (1543 CE): Nicolaus Copernicus, a canon at Frombork, published De revolutionibus in 1543, placing the Sun rather than the Earth at the centre of the universe. It began the Scientific Revolution.
Rembrandt (1606 CE – 1669 CE): Dutch painter and printmaker from Leiden who worked in Amsterdam. A master of light and shadow, he is considered the greatest artist of the Dutch Golden Age.
Johannes Vermeer (1632 CE – 1675 CE): Dutch painter from Delft known for quiet interiors filled with soft daylight, such as Girl with a Pearl Earring and The Milkmaid. He painted slowly, and only about 35 of his works survive.
John Locke (1632 CE – 1704 CE): English philosopher and physician, a founder of empiricism and liberalism, whose Two Treatises of Government and Essay Concerning Human Understanding argued for natural rights, government by consent and knowledge from experience.
English Civil War (1642–1651 CE): A series of wars between Royalists loyal to Charles I and Parliamentarians. Parliament won, the king was executed in 1649, and England briefly became a republic.
Isaac Newton (1643 CE – 1727 CE): English mathematician and physicist at Cambridge who formulated the laws of motion and universal gravitation, co-invented calculus and advanced optics.
Industrial Revolution (c. 1760–1840 CE): The shift from hand production to machines, factories and steam power that began in Britain around 1760, centred on textile towns such as Manchester. It spread to Europe and North America and transformed work, cities and the world economy.
Watt steam engine (1769 CE): James Watt patented his separate condenser in 1769, greatly improving the steam engine's efficiency. Built with Matthew Boulton in Birmingham from 1775, it powered the Industrial Revolution.
Albert Einstein (1879 CE – 1955 CE): German-born theoretical physicist who developed the special and general theories of relativity and explained the photoelectric effect, for which he won the 1921 Nobel Prize in Physics.
Adolf Hitler (1889 CE – 1945 CE): Austrian-born dictator of Nazi Germany from 1933 to 1945. He started World War II in Europe and bears chief responsibility for the Holocaust. He died by suicide in Berlin.
October Revolution (1917 CE): In November 1917 (October in the old calendar) Lenin's Bolsheviks overthrew the Provisional Government in Petrograd, storming the Winter Palace and creating the first communist state.
Russian Revolution (1917–1923 CE): The February Revolution of 1917 in Petrograd ended the rule of the tsars, and the October Revolution brought Lenin’s Bolsheviks to power. After a civil war they founded the Soviet Union in 1922.
World War II in Europe (1939–1945 CE): The European theatre of the deadliest war in history, from Germany's invasion of Poland in 1939 to its surrender in May 1945. Tens of millions died, including six million Jews in the Holocaust.