1397 - The Kalmar Union
By marrying the Norwegian king and simultaneously being sovereign of Sweden, the Danish Queen Margrethe I set the scene for the founding of the Northern Alliance formalised as the Kalmar Union in 1397.
Later, her grand nephew Erik VII came to power and paved the way for Copenhagen's expansion as Denmark's capital by making it his permanent home, having seized control of the city from the Catholic Church in 1417. Copenhagen's location at the centre of the region was pivotal to its subsequent growth as a trading port and military and political centre.
Erik's successor, Christian I, was the first king to be crowned in the city. He rebuilt Copenhagen Castle and founded the country's first university, Copenhagen University, in 1479.